Dyson Spheres!

Something that probably belongs on Puffy's Blog, but actually I just came on the website because I'm reading Larry Niven's "Ringworld" (since I'm suffering from "Discworld" withdrawal) and I wanted to know what Dyson spheres are. So. I can be dorky too. BTW, I have to note that every post I put on Puffy's blog is actually a quote from Puffy. This is more than can be said for the things that Nick and Alex post.