I like using Icon Archive. They have some really great icons that fit a wide variety of situations.

Also, if you don't mind paying some money, you can look into vWorker. You place your request in for whatever you want and the max money you're willing to pay. Then workers bid on the job and you select the person you want to work on your project. You can even have them sign NDAs if you need it. The money is escrowed into vWorker but is not released to the worker until you accept the final work.

And lastly, the general developer forum is usually best for things like this