Here’s my list of markets, kitchen stores, and other Montreal foodie stuff to get you started.  Additions to this list will be ongoing.  This list is largely focused on NDG and central Montreal but additions are welcome.
If you are making a long trek, PLEASE call before hand.  I cannot vouch that at any moment all this information is up to date.

Bakeries & Patisseries

Boulangerie Guillaume, Mile End – 17 Fairmount Est, 514-507-3199 Artisinal organic bakery

Patisserie Rhubarbe – 5901 de Lanaudière, Montreal H2J 3P9 514-903-3395
This is considered one of the best patisseries in the city.

Patisserie de Nancy, NDG – 5655 Monkland, Montreal H4A 1E5 (514) 482-3030

Cho’cola, NDG – 5601 Monkland, Montreal H4A 1E4 (514) 485-2652

Première Moisson – There are many branches throughout the city including Monkland, Bernard, and Atwater Market

Patisserie de Gascogne – Patisserie with 4 locations including Laurier and Sherbrooke in Westmount.
Mamie Clafoutie – Bakery with 4 locations including Van Horne and St-Denis

Butchers

Boucherie de Tours, Atwater Market
Ferme Nordest, Marché Jean Talon – meats from animals raised without antibiotics and hormones

Boucherie Saint Vincent, Atwater and Marché Jean Talon – local organic meats

Le Maitre Boucher, NDG (Monkland) Monday -Wednesday 8h30 – 18h55, Thursday – Friday 8h30 – 21h00, Saturday 8h30 – 17h00, Sunday 10h00 – 17h00 – A great selection of pre-prepared meals, cheeses, and marinated meats.  They carry meats from small farms with sustainable practices.

Chez Vito, Mile End – 5180 St-Urbain, 514-277-1981 A great neighbourhood butcher.

Cheese

Fromagerie Atwater, Atwater Market

Yannick Fromagerie, Outremont – 1218 Bernard, Outremont, H2V 1V5 (514) 279-9376 – There are also locations in DDO, Saint-Jérôme, and Québec City

Fromagerie Hamel – Marché Jean Talon, Marché Atwater.  There are also locations on Mont-Royal East, Sherbrooke East, and Repentigny.

Markets

Marché Jean-Talon, Villeray – Montreal’s largest market

Marché Atwater, Atwater – A smaller but still excellent market located near downtown

Kitchen Stores & Baking Supplies

La Soupière, near Concordia (Downtown) – a very well stocked no-nonsense kitchenware store

Vixit – 290 Henri Bourassa Ouest, Montreal, QC H3L 1N7 514-337-0814 – This looks like a pretty intense shop with 2 floors, and their website advertising the most complete line of cake decorations in North America!  Obviously more aimed at the trade than your average consumer, but I am sure any cookware fan would go crazy there.  They also have a pretty extensive online shop.

Les Touilleurs – 152 Laurier Ouest, Montreal, H2T 2N7 514-278-1193.  A pretty high end kitchen store located in the Mile End.  They also do workshops.

Quincallerie Dante – 6851 St Dominique, Montreal H2S 3B3  514-271-2057.  This is a classic kitchenware store located in Little Italy

Arthur Quentin – 3960, rue Saint-Denis, Montreal, H2W 2M2 514-843-7513.  Another lovely upscale kitchen store located in the heart of the Plateau.  Arthur Quentin also has an atelier with marked down products!  L’Atelier, Solderie des magasins Arthur Quentin and Bleu Nuit, 4247, rue Saint-André

Cuisine Doyon – 8505, boul. du Quartier, Brossard, J4Y 3K4 (plus another location in Quebec City).  They also have an online shop.

BSA – 6005 Blvd Couture, Montreal, QC H1P 3E1 514-852-2719 Meat making equipment such as cultures, salts, knives, etc.  The sales counter is at the first part of the building next to the loading docks.  I found this off Chowhound so this info is unverified.

Chocolats Privilege – various locations including Atwater Market and Marche Jean Talon.  They offer a variety of chocolate baking supplies.

Specialty Bookstores

Appetite for Books – Specialised cookery bookstore in Westmount

Spices

Épices de Cru, Marché Jean Talon – A huge variety of spices from all over the world.  They also have a great online shop.

Spice Station, 174A Bernard Avenue (Mile End) – see an article on this store here

See also the wholesale/bulk section below.

Specialised Grocers

Asian

Marché Hawaii – Ville Saint Laurent (1999 Boulevard Marcel-Laurin) – despite the name this is an Asian Grocer.  See the review here

Beer & Wine

Épicerie Unique – Le Dépôt de la Bière – 4109 St-Laurent, 514-489-8939
Here you can find a variety of Quebec microbrews and most are available by the bottle.

Dutch

La Bernoise – 3988 Blvd St. Charles, Pierrefonds 514-620-6914

Warta – 16043 Boul De Pierrefonds, Pierrefonds 514-624-6228

European

La Vieille Europe – 3855 St-Laurent (corner Roy)
A large selection of imported products including cheeses, charcuterie, jams, teas, etc.

Euro Deli Batory – 115 St. Viateur West (corner St-Urbain) 514-948-2161
I believe this is Eastern European focused.

German & Austrian

Boucherie Atlantique – 5060 Côte des Neiges, Corner Queen Mary
A German delicatessen which also carries a wide variety of European specialties.

Vienna Pastry – 297 Blvd St-Jean, Plaza Pointe Claire

Indian

The section of Jean-Talon West between l’Acadie and Parc has many Indian grocers and is known as Little India

Marche Victoria Orientale – 6324 Av Victoria, Montreal (Victoria corner Kent)

Marché Jolee – 5493, av Victoria, Montreal, QC H3W 2P9 514-733-6616

Italian

The Italian Pantry, NDG (Monkland, corner Beaconsfield) – an enthusiastically run specialty grocer

Pasta Casareccia, NDG (Sherbrooke, corner Draper) – a restaurant and shop selling fresh pasta and food

Korean & Japanese

Marché d’Alimentation Coréenne, NDG (Sherbrooke, corner Beaconsfield)

Miyamoto, Westmount – 302 Victoria, 514-481-1952 – Specialist in Japanese Foods

Jang Teu  – Westmount/NDG – 2113 Décarie 514-932-9777 – Specialist in Korean and Japanese Groceries

Latin/Mexican

Supermarché Andes – 436 rue bélanger, H2S 1G2 (corner Saint Vallier) Metro Jean-Talon

Mundial – 7130 Casgrain 514-271-6171 A latin butcher located on the west side of Marché Jean Talon which sells meat and cheese including a house crema (soft Mexican cheese) and fresh chorizo.

Tortilleria Maya – 234 Jean-Talon East 514-495-0606

Amaranto, NDG (Monkland, corner Hampton) 514-510-5225
A small restaurant which also sells a selection of Mexican groceries.  I’d call before hand if you are looking for a specific item.  Have something to eat while you are there – it’s excellent!

Che Churro, 6543 Ave. Somerled, Montreal H4V 1S7 (514) 303-8316

Librarie Espagnole, 3811 Saint-Laurent.  These guys also appear to have an online shop.

Sabor Latino, 4387 Saint-Laurent, 514-277-4130  They also have another location on Belanger and St-Vallier.

Middle Eastern

Akhavan Supermarchè, NDG (Sherbrooke, corner Beaconsfield) – fantastic marinated meats and sweets

Organic

There are so many to list, but if someone has any favourites I’d be happy to put them up.  In the meantime here is a list.

Polish

Felix Mish – 1903, rue Joliceour, H4E 1X4 514-766-2094
Polish deli with kielbasa, etc.

Wawel Patisserie Boulangerie – 5499 Sherbrooke Ouest, 514-483-1042
Polish Bakery

Chopin Inc. – 4200, boulevard Décarie H4A 3K2 514-481-0302
Charcuterie

Charcuterie Varsovie – 5357 5 Avenue, Montreal, QC H1Y 1X8 (514) 728-5034

Polonia Polonia – 383 de l’Eglise, Verdun H4G 2M5 514-362-8875
Charcuterie

Quebec Foods

Marché des Saveurs, near Marché Jean Talon – specializes in Quebec artisinal foods and beverages

Le Canard Libéré, 4396, St. Laurent, 514-286-1286 – the Brome Lake Ducks shop selling all these duck from these Quebec Producers

Fou d’Ici – 360 de Maisonneuve Ouest, H3A 0G6 (Maisonneuve & Bleury) – Grocery store specializing in local producers.

Romanian

Bucarest Charcuterie & Patisserie – 4670, boulevard Décarie, H3X 2H5 514-481-4732

Russian

Vova Patisserie – 5225 Parc, 514-278-3411 – Stocks some russian products.  Not really a dedicated Russian grocer.

St. Petersburg Russian Delicatessen – 5462 rue Sherbrooke Ouest, Montreal, H4A 1V9 514-369-1377  A smallish Russian grocer in NDG selling a wide variety of Russian prods.

Ella’s Deli – 4968-B Queen Mary Road, 514-904-0925 & 555 Westminster, #100 Cote Saint-Luc 514-368-1741 (a second location).  ellasdeli@hotmail.com  These appear to be large well stocked Russian Grocery stores.

There’s also a list of shops on the Russian Pages Montreal

Swiss

La Pendulerie – 2080 Crescent St. H3G 2B8 514-499-0626
This store sells clocks, Swiss chocolate and other Swiss foodstuffs.

Vegan

Viva Vegan Store – 4148 St-Laurent, Montreal, QC 514-903-8426

Warehouse/Bulk

Mayrand – 5650 Metropolitan Blvd. East, Saint-Leonard, H1S 1A7
Never been there but it looks like if you are really looking to stock up, this may be the place to go!

Épices Anatol Spices – 6822 St-Laurent Blvd, H2S 3C7 514-276-0107
This place looks insane with 60 varieties of tea, 150 herbs, and 600 spices.  They also have 90 kinds of nuts, flavour essences, candied and dried fruits, etc.

Online

Terroirs Quebec – http://www.terroirsquebec.com/eng/

Les Delices de l’Île d’Orléans – French only website
Quebec producer selling everything from vinegars to terrines.

Marché Transatlantique – A crazy amazing online selection of all things good and gourmet.  Foods range from truffles, charcuterie, salts, to fish, seafood and caviar.  They are located in the Mile End and I believe you can visit (although I’d call ahead to confirm), but the largest selection is online.

Golda’s Kitchen – A Canadian online bakeware, cookware and cake decorating resource.  Great for finding packaging and all sorts of other kitchen stuff you never knew that you needed!  I’ve used them a few times and they are pretty quick and reliable.

Vixit – For those who don’t want to go to their shop in person they have a pretty extensive selection.  See my description of this location under Kitchen Stores above.  They seem to focus on baking and cake decorating.

Random

Kitchenaid Repair
La Flamme Electrique – Rue Amherst

Some of these ideas come from the blog The Mindful Table