Texas Flood - SRV (still sounds great)
March of the Saint - Armored Saint (doesn't sound dated at all)
Black Sabbath - Black Sabbath (still as heavy as hell)
The Plague That Makes Your Booty Move - Infectious Grooves (what's not to love about Sarsippius?)
Liquid Tension Experiment - Liquid Tension Experiment (amazing what some guys can do in a week)
Kill 'Em All - Metallica (one of the great thrash albums of all time)
Blizzard of Ozz - Ozzy Osbourne (Randy Rhoads, all you need to know)
Suicidal Tendencies - Suicidal Tendencies (some classic songs)
The Legacy - Testament (another classic thrash album)
Texas Sugar/Strat Magic - Chris Duarte Band (great blues/rock)
Appetite for Destruction - Guns 'n Roses(the only album I actually like by them)
A few other bands had good debuts (Slayer, Anthrax, Sepultura, Dream Theater, Megadeth, etc.), but they didn't do much for me. Listen to them once in a while, but I much prefer later albums from them. And, there's a few others (Overkill, Pantera (Cowboys doesn't count), Motorhead, etc.) that I haven't actually heard yet, but plan to hear sometime in the future.