Guru.com is a great site. I've used both Guru and Elance and I've found that Guru buyers are "business owners/companies" while Elance "buyers" are more of the get rich quick types. I'd suggest you try Guru first--it's also less expensive. Elance will eat you alive with their fees.
Plus one thing you should know about Elance (which not many do) is that there is a huge conflict of interest on the site. Elance has its own network of writers and freelancers bidding and Elance is very involved in "recommending" freelancers to buyers.
http://www.freestuffandsamples.com/constantcontent.htmlThis site is great because you can write about whatever you want, and let editors buy it, or you can take "requests". It is used by thousands of editors and web site owners.
Also, check "writing" jobs on Craigslist.org. They have a lot of great freelance jobs.
Another one is the freelance writing exchange. They list freelance, work-from-home, and numerous other projects. You can apply directly via their website. Right now you can try it out for only $2.95.
http://www.freestuffandsamples.com/fwe.html