I like your idea, but a few thoughts/questions...
When you it's built to "search through the clip archive" - what archive are you referring to? If it's the automatic archiver that saves every ATC feed, it would be very hard to catalog. I guess we could build a parser to grab flight info from the affected airport, but Center feeds would be out of luck.
The uploaded clip would work great though. Maybe instead of uploading a clip, something can be worked out that you upload to the site and the site will auto-create a thread on here.
I noticed you used the IATA flight codes, rather than the ICAO ones... just curious why your preference? (It doesn't matter, I'm just curious!)
As for dorishd's comment... "It will come in handy" - yes, definitely! ..."when the major news organizations want something!" - that part worries me. It's part of growing pains, and we gotta take the bad with the good, but the news seems to report more bad news than good and I'd hate LiveATC to be used for something in a negative light.
Nonetheless, I think this is an awesome idea. I think with a little more thought/drafting, this will turn out well.
Great idea, Blake!