Online

Discussion forums

Indiamike discussion forums - Great source of info of all kinds for expats and travelers all over India. Sprawling site with lively discussion forums.

Main site: http://www.indiamike.com

Bombay page: http://www.indiamike.com/india/mumbai-bombay-f22/

Moving to Mumbai page: http://www.indiamike.com/india/moving-to-mumbai-f101/

Lonely Planet Thorn Tree Forum: India - Mostly questions and answers pertaining to short term travelers but some good stuff.

http://www.lonelyplanet.com/thorntree/forum.jspa?forumID=16&keywordid=66

Tripadvisor Bombay forum - Again, mainly Q&A for short term travelers

http://www.tripadvisor.com/ShowForum-g304554-i4228-Mumbai_Bombay_Maharashtra.html

Food & drink

Burrp - Best source for user-generated restaurant & bar reviews

http://mumbai.burrp.com

Events

TimeOut Mumbai - Lots of information, but hard to navigate their crappy website

http://www.timeoutmumbai.net

Offline

Events

TimeOut Mumbai - semiweekly magazine. highly recommended for restaurants, movies, plays, news, goings on about town, etc.

"Social groups and clubs"

Mumbai Connexions - Expatriate women’s club open to all nationalities. Publishers of the Namaskar Mumbai guidebook.

http://www.mumbaiconnexions.com/

American Women's Club - pretty self-explanatory? Social and charitable group in Bombay.

http://www.awcbombay.com/

Guidebooks

Love Mumbai - The Love guide "handbook for the luxury vagabond" is an excellent, extremely well-curated guidebook to Bombay, geared more towards expats and others with longer timeframes or larger wallets. Available at Anokhi, Dhoop, Indigo Deli, Bungalow 8, and elsewhere for ~ Rs. 1500 or so

See http://lovetravelguides.com/country/india/mumbai.html

Namaskar Mumbai -

http://www.mumbaiconnexions.com/namaskar_mumbai.html

Lonely Planet - of course. None of the LPs I have seen have too much depth on Mumbai beyond the basics, however.

TimeOut Guide: Mumbai & Goa - Happily caters just as much to residents as tourists. E.g., lots of info on shopping compared to other books.

Outlook Traveller: 52 Weekend Trips from Mumbai - Recs are sometimes hit & miss, but lots of great info about places you'll never find in Lonely Planet.

City Map

Eicher City Guide - Must-have map book. Will help you make sense of crazy streets and neighborhoods and find obscure addresses. Just know that nobody in Bombay looks at maps or knows and street names.