Most of these are stolen from MetaFilter.
Welcome back to public blogging, Dan.
Musical instrument samples. My first UROP at MIT was at the Media Lab, where I helped record instrumentalists as part of a musical instrument identification system. Paris Smaragdis was there at the time, and now he is at UIUC where he has a lot of cool audio demos. There are also some great clips Inside the Music Library at the BBC.
Ridiculous computer interfaces from movies.