Craigslist, Rooms/Shared section, starting point of my Seattle housing search. Here's the attributes of my ideal house, in order of importance:

• 5+ cool housemates, gender balanced
• Urban neighbourhood, not suburban, low-density, all-residential
• Walking/Biking distance to work
• Super close to groceries, like two-minutes-walk close
• The house itself should be old and lived in, not new and sterile feeling
• Close to YMCA and climbing gym
• ...

In fact, I want something exactly like 3623 St Urbain, my place this past summer in Montreal.

A related item of interest is the "Best Of Craigslist" page (RSS), where you'll find the posts voted funniest/weirdest/coolest by readers. MY CRAZY GIRLFRIEND made me laugh recently.