I've been wondering about using a SheevaPlug for a LiveATC site! Seems like a great idea. Are there any reasonably priced small USB scanners out there? I've seen the Icom PCR series, and the WinRadio as well. They're all very expensive. I might be able to get a feed somewhere if there was a small (SheevaPlug) solution that could be entirely remotely controlled, to add/drop frequencies etc.
Can you share any more information?