It seems a bit odd to use your computer resources to mine bitcoins and then donate them to SETI or folding@home when you could simply donate some computer power to those projects directly.
... yep there are many way to contribute to a project. Bitcoin donations are just one of the way you can help. I remember installing the SETI client years ago and it blew my mind to think of the project that I was in some small way contributing to. Interesting to think of the bitcoin mining parallels though.