Hiring Artists for Open Source Projects?

MikeFM asks: "What is the best way for an Open Source developer to hire artists to provide graphics, music, and other artwork for Open Source projects? I need to hire such people and I'm not sure where to go or how best to spell out the terms of the contract so that it's okay to release the works for hire as Open Source. I'm willing to pay but can't afford to pay a lot. It seems to me that providing artwork for an Open Source project sounds like great exposure to art students and artists still early in their career but how do I find these people? I've posted ads in the local schools and art stores.. what else can I do?"