Upwork (previously oDesk) – It accommodates both short- and long-term projects, hourly or per-project work and expert-level and entry-level engagements.
Freelancer – Lots of project-based work in many different industries.
People Per Hour – If you’re a designer, web developer, SEO specialist, etc, this is a great platform to look for freelancing projects.
iFreelance – Hundreds of freelance projects to big on. You keep 100% of your earnings. Paid membership required.
Project4Hire – Companies and business owners looking for programmers, designers and writers.
GetACoder – Website programmers, designers, and writers need for small scale projects.
Guru – Tons of jobs to choose from Admin Support to Legal jobs.
Toptal – Toptal caters to more experienced freelancers. You must go through an intense screening process but can get work through very prestigious companies and you will not have to bid on jobs.