I have no idea and would not know how to go about figuring it out, simply because I've forgotten about a lot of shows I've attended. And that's just for actual, signed bands. When you factor in tribute bands and cover bands, who knows? But I'll try to list some of the notables below:
First show ever: Quiet Riot, Whitesnake, Kick Axe at the Oakland Colosseum (now Oracle arena), September 22, 1984.
I saw Whitesnake twice after that: once as final warmup act in a festival (Day on the Green in Oakland) with Motley Crue, Poison, and Jetboy, for the s/t album, and then headlining on the Slip of the Tongue tour in Columbia, MD (I think Faster Pussycat opened).
Def Leppard 3 times: Hysteria tour (Oakland, with Tesla opening), Adrenalize tour (Oakland--I forget who opened), and then years later co-headlining with Journey when they had JSS. I think Def Leppard was touring on Yeah! that time, but it could have been Sparkle Lounge.
Siouxsie & the Banshees once in Berkeley around 1987 or 1988, with Julian Cope and Andy Sommer opening.
U2 at a festival in Oakland in 1987 or 1988 with The Bodeens and The Pretenders opening.
Depeche Mode in Mountain View in early 1988.
Y&T numerous times from the late '80s to the present, as well as the Meniketti solo band a few times as well.
Megadeth headlining a festival in Minneapolis with Fear Factory, Flotsam & Jetsam, and Korn opening in summer 1995.
Van Halen with some popular but awful '90s band I can't remember the name of in Minneapolis in summer 1995.
Britney Fox headling with Nantucket and Warrant (before Warrant had released their first album) in late 1988 in North Carolina. Saw Britney Fox again at a little club in Panama City Florida in early '92 touring in support of Bite Down Hard.
Queensryche: I've seen them a few times and feel like I may be forgetting a show or two, but here's what I recall: Building Empires tour in late '91 in Raleigh with Suicidal Tendencies opening. Promised Land tour in San Jose with Type O Negative opening (this is a HEAVILY bootlegged show). Live Evolution, night #2, in Seattle. Twice with DT in 2003, I think it was (Concord and Sacramento). Once on the Take Cover tour in Portland. Once with Todd on the last album cycle.
DT: 11 times, starting on the summer tour with Satch and King's X after SDOIT was released. I posted about those shows in the DT tour thread.
Lacuna Coil awhile back on the Shallow Life tour, with a bunch of garbage bands opening.
Saw Tesla a couple of more times in the '00s.
Transatlantic in Downey on the Whirlwind tour.
Neal Morse Band in SF last month.
I dunno...several more.
~~~~~~~~~~~~~~~~~~~~~~~~
Concert wish list for bands I still want to see or really want to see again:
-Epica
-Lacuna Coil (again)
-Maiden
-Symphony X