I don't know which boardhouse Stu is using, but for 1-2 layer boards suitable for hand soldering, www.olimex.com is by far the cheapest that I've found. They also accept EagleCAD files directly, and for non-profit hobbyist use a limited version of EagleCAD (pcb <= 4"x3", including auto-routing) is available gratis. The only gotchas with olimex that I can see are that they tin the boards before soldermasking them, which means that they aren't really suitable for reflow/wave soldering, and that they are based in Bulgaria, which may not be optimal for credit card ordering. (Note that I haven't heard/seen any evidence that suggests that this will be a problem, but I'm generally wary of sending my CC number to a formerly eastern block country). On the positive side they will do free panelisation/de-panelisation, which means that if you had a 1"x2" board then you can pay for an 8"x11" panel, and they will fit as many of your pcbs onto it as possible, and then cut them free afterwards. For small boards this is a bonus - most houses have a panelisation set up fee and a per-board depanelisation charge.

IIRC, the next cheapest that I've found is www.custompcb.com. Full SMOBC (suitable for wave/reflow soldering), and still fairly cheap. Although based in Malaysia, they use a US-based CC payment agency, so your CC number supposedly never leaves the US. They appear to be a professional setup from what I've read on their web-site. But you have to pay extra for silkscreening and soldermasking. They also accept EagleCAD directly.

If anyone has any other cheap EagleCAD-accepting contenders, please post!