- Advanced Circuits
A personal favorite. They're on the higher-end of board manufacturers price-wise, but if you want to make sure your boards are done right first time (manufacturing wise, you still have to design working circuits) with a professional look, these are the guys to use. They typically have discounts for students as well. They also have a Design Rule Checking (DRC) service too, to make sure will come out right the first time.
A Sparkfun offshoot, they group boards together until they can run a full panel, to get the cheapest price possible. If you just want a decent-quality board cheap, and don't mind the timescale as much, this is a good bet.
The Portland, Oregon dorkbot group that does PCB fab on the side. Similar to BatchPCB, they group orders together until they have enough to do a full panel run. I've heard mixed things about these guys, and that it might be kind of dead recently. Worth a shot if you need super-cheap boards fabbed.