This sounds very interesting. It could be interesting to see if the mining rigs could be used to do other calculations as well. And what calculations would be beneficial?

Render movies / Animations
Cracking passwords

What else could it be used for? Because I would be nice to make a more open client - to mine other stuff than just bitcoins. And the people could just buy the mining with bitcoins.
Come with some ideas, maybe we could throw something together.