The folks at JPL have installed a live webcam in a balcony overlooking the clean room where the next Mars rover, Curiosity, is being built. So you can watch smart NASA and Caltech people build a rover that's going to Mars!
[Update: Sigh. Of course I post this on a Saturday morning when no one is working. But check back every now and again; I was watching on Friday afternoon and it was busy! And make sure you note the size of the rover; it's far, far larger than the previous ones.]
There's no audio, so don't bother with sound. But on the UStream page linked above there's a chat room.
If memory serves, what you're seeing is the same clean room where Spirit and Opportunity were built; I visited JPL a few years back and saw them both being put together there. It's amazing to look down on hardware you know is going to another planet.
Yay smart people!