Elance is the Internet's biggest marketplace for legitimate freelance work. And, it's my personal favourite of all the websites in this list.
It provides a simple interface that allows you to search for jobs in any kind of niche. From Writing and Translation, to Web Design and Programming.
Basically, people post jobs they want doing on the website, and you submit a proposal for it. It's that simple.
Regardless of how much money you want to make, the possibilities are endless: there are freelancers on subscribed making $1,000 to $100,000 a year.
Pros: Free service. Simple to use. Easy to manage Tax Documents. Verified, trustworthy jobs.
Cons: Can be slow to become established. Bad Freelancers willing to work for $1-$2 an hour.