What freelance sites have you used in the past, and what was your experience with them? Specifically I'm looking to do software/IT.
http://odesk.com As a software/IT provider, you're required to prove that you're working through the day, either through a webcam or updating your work diary often. For this extra overhead (which isn't a big deal), you aren't required to purchase a paid account. The same level of competition exists here, however. Your reputation, and the need to build your reputation when you first start, also applies here.
http://www.guru.com Similar to Elance, you have better chances if you sign up for a paid account. Some gigs even require a paid account. Competition is also high, as is your reputation and the need to build your reputation when you first start.
http://programmermeetdesigner.com Haven't used this service before. Without the quality controls that Elance & oDesk have, I suspect the quality of the gigs & clients may vary. It's also not as well-known, so there is relatively less competition.
http://craigslist.org I don't think I have to tell you to avoid this site for finding freelance work like the plague.
Good luck!