Elance.com
This is best place for finding jobs on article writing, web designing, copy
writing, creation of ebooks etc. They also provide escrow service for
employers as well as employees.
Note:Membership fees is present

Guru.com
Guru.com is an excellent site for finding freelance jobs for your sites.Presently there are more than 5000 jobs on which you can BID upon.
Note:option of being a paid or free member.

Rentacoder.com
This is a haven for freelance programmers and developers. This also provides
an Escrow service.
Note: free to join but requires you to pay a commission on each project you complete.

Getafreelancer.com
You can expect a lot of jobs being posted on this site. The interface of the
site sucks when compared to elance.com or guru.com. But there are lot of
jobs on which you can bid upon.
Note: Free to join. Option of upgrading as gold member at 10$/month. Gold members have access to special projects. Free members only have 15 bids.

Other top freelance sites

scriptlance.com
Site similar to rentacoder.com

project4hire.com
Site similar to rentacoder.com

Allfreelancework.com
Nice freelance site. Interface is a bit confusing intially. This site even
provides a lot of resources on learning freelancing. Basically this site is good for beginners.

Programmingbids.com
Upcoming site. Not so many jobs as on the above sites.

Forums.digitalpoint.com
This can be a good place for beginners who looking to build a portfolio. No cost to join but expect to do slave labour. Because of te competetion present at this forum the one who can provide quality work and cheapest prices can expect Jobs. But the important part is you will build a portfolio easily using which you can land high paying Jobs on elance.com or guru.com.