There is a great guide on Instructables for building a "hackduino". It's an arduino compatible board, minus the in-system programmer. Essentially, you just need an actual Arduino to program the device. This is great because the devices can be built for around $10 a pop w/ low volume pricing, and are great for embedding into more permanent projects (instead of sacrificing your $30 arduino).

These might even be a great fund-raising mechanism, if we can make them a little more user friendly (e.g. programmable w/out an existing Arduino). I think we would just need to add the USB controller chip to achieve this.