Hell, I must have at least 200 or so shows from my favorite bands. The earliest show I have is Black Sabbath's first US show. The most recent is Iron Maiden's Rosemont show from 2008. A few of these concerts were traded by tape, most of them were downloaded from a friendly bootleg ring I used to be part of. Along with these came a few rare goodies, such as demo tapes and "secret" gigs. The thing that's a disappointment to me the most is that the very few times any of my favorite bands play in my hometown (Fort Wayne, IN) the show was either never recorded, or hasn't been found yet.

I'm probably going to try and organize all of them when I feel like it. But to do that I have to go through the countless data CD's that have all the gigs.

My list of some of the coolest stuff I have [note, this might be changed as I look through my stuff]:
-Megadeth: first gig: Kerry King on guitar
-Megadeth: "That One Night" audience recording (full gig, all songs)
-Metallica: Second gig (first show hasn't been found to this day)
-Metallica: Cliff's first show
-Metallica: Kirk's first show (contains the one and only time Metallica played "The Mechanix" without Dave Mustaine)
-Slayer: Demo tape (from either late '82 or mid-'83)
-Slayer: "Live Undead" gig
-Iron Maiden: Bruce's first show, 1981 (I think I have Nicko's first show somewhere too)
-Iron Maiden: Maiden Japan (full gig)
-Black Sabbath: First U.S. show (I think this one might be gone)

I'm sure I could list more, but I have to look through all of these things.