Hmmm...
Well if you go by number for projects its freelancer (.com most crowded as well) and if you want to go by the sophistication peopleperhour (.com I personally like this site more).

There's also vWorker (.com, used to be rentacoder) and elance (.com)

Typically these sites should be used to find somebody you can develop a relationship with long-term. I'm not affiliated with them, but I've found bpovia (.com) to be a pretty reliable outsourcing shop.

Hi Nick, I would like to recommend a firm/company. It has a far more advantages compare to a a freelancer. The staff that you lease are backed by a good management and technical team also, your files and data are secured and confidential. Your lease staff is 100% working for you and dedicated, the people you the above freelance sites all freelancers. working from home and maybe working with other clients at the same time.

freelancer.com or try rockettheme.com they provide web design services.

You could try odesk as well. I've been hiring programmers online for many years, and have found that the site I use has little to do with the quality I receive, which is the most important thing (well, quality and price, of course). If you have time, I'd recommend small test projects with multiple programmers, before embarking on a larger project. A large project with an unknown coder is a recipe for disaster (I've learned from experience). Properly documenting your project is also recommended. Use a tool like balsamiq and give your programmer something to visually look at...it really helps. Good luck!

Go with oDesk (the cheapest). Get a Russian or Ukrainian guy (best programmers around). Hire on a fixed fee (the safest method). Pay when you see results. That's all.

Yep! oDesk or eLance. Pay per job, not per hour. There are a LOT of great programmers out there (example: Indian, Philippines and Ukrainian).

Make certain you write up a very specific specs, including language, style and methods, documentation standards (if important) etc... Spending an hour ahead of time defining exactly what you want will save you frustration and unmet expectations on the back end.

Good Luck.

Oh yea...
The cheapest programmer is not always the best. An example, I recently put out a job and got a range of bids from $147 to $700. I ended up paying about $300 and got a great value.

Im a programmer and sometimes go looking for work on the freelance sites. I usually use donanza.com to do the searching for stuff that i want to do, so it doesnt really matter so much where the project is.

But as for the hire on a fixed fee option you can get yourself into issues if you dont know exactly what you want. If the project requirements are vague or the project poster doesnt really know what they want, then pay by the hour allows you to change your mind as you go.

If you hire on a fixed fee, the programmer is going to want to know exactly what you want made before you start so they can know how much to bid.

Something like "Some design touchups to my site" is not the kind of project that its possible to know how much to bid a fixed fee on. But the same project on an hourly rate and you can keep going until its all done.

Hire a programmer on a fixed rate for a job that is un-finishable and you will soon find it very difficult to contact that programmer once they realize that there is no way to finish the project.

One thing to keep in mind, when using those freelancer type websites, is that many people will bid on your project, even if they have no clue what they're doing, in hopes that they will figure it out on-the-fly. Pay attention to the bids. If a bid seems to low to be good, the person probably doesn't know what they're bidding on, and may not be able to complete the job.

It's even better if you find someone who has ALREADY done that kind of job before.