I have been wanting to link to a builder of a small gas turbine, but I wasn't terribly interested in the usual automobile turbocharger conversion -- Didn't seem terribly useful to the typical BD.N reader, but then I found the Gas Turbine Builders Assocation. They have examples of some very nicely made little jet engines, something you could actually put on a R/C plane and fly. Looks like fun if you have access to a lathe and have some real machining skills, well worth a look.