I agree with Dionysus,
I can't see myself living without someone either, I live with THREE girls in a house! Sure it's a little difficult to keep money and chores divided fairly and to make sure everyone does them (i'm often reminded of being house president when it comes to this), but we're all 24 and I don't want to move out any time soon.
I would definitely do a craigslist listing with flexible age limits depending on other circumstances (full time job, etc) and definitely check out grad students in the area (I've had many friends and sisters that got their apartments in grad school thru checking posters and stuff around campus or through craigslist)
i did a quick google search and found
roomster.net
and
roommates.com
idk how useful it is, but it's worth a shot