Mad props to all the people who confessed to shows like New Kids on the Block and Tiffany. All my list does is remind me that I've seen some really crap people in concert, in addition to the good ones:
Kiss (1976 or 77)
Shaun Cassidy (oh yes!)
Bay City Rollers (hey, I was 8, and they rocked!)
The Who
Van Halen (with David Lee Roth and also with Sammy Hagar later on)
Aerosmith
Motley Crue
Ozzy Osbourne (Let me just interject here that I was a pre-teen metalhead.)
Bruce Springsteen (11 times)
U2 (loads of times)
The Grateful Dead (I don't dare to count how many times)
Jimmy Buffet (more than 10 times but less than 20... and I say that more to clear the air than out of pride at the fact.)
Dan Fogelberg
Peter, Paul and Mary
Barry Manilow
Bette Midler
Neil Diamond
John Denver (um, I live in Colorado.)
Poison (Warrant opened so I won't count them separately.)
New Order (Crap.)
Depeche Mode
PiL (Double crap.)
The Sugarcubes
Ziggy Marley & the Melody Makers
Duran Duran (1984)
Power Station
The B-52s
Metallica
The Hooters (what an unfortunate name...)
Megadeth
Guns N Roses
Peter Murphy
Gordon Lightfoot (I did this to impress a guy.)
Love & Rockets
The Samples (I think they were just a Colorado thing, though.)
Burning Spear
Third World
The Rolling Stones (4 times! And I'm not even a big fan!)
The Dixie Chicks (Warning: here comes my country phase...)
Brooks & Dunn
Reba McIntyre
Leann Rimes
Chris Ledoux
George Strait
Tim McGraw
Faith Hill
Toby Keith (of which, I am now deeply ashamed)
Elton John
The Monkees, ca. 1986 or 1987??
Sting
The Fixx
Frankie Goes to Hollywood
Madonna (1985)
Journey
Eric Clapton (8 times)
Kenny Wayne Shepard
Jonny Lang
Phil Collins (1985)
Pink Floyd
The Cars
Sarah Brightman
Steel Pulse
Stevie Ray Vaughan
No Doubt
Red Hot Chili Peppers (w/Snoop Dogg!)
REM
Cranberries
Sonic Youth
Hole
David Bowie
Indigo Girls (6 times. I like them. They're like the Dead -- they do a different show every night.)
Phish
Barenaked Ladies
Pearl Jam
Soundgarden
many a Warped Tour
many a Lilith Fair... okay, two years in a row
The worst artist I've ever seen in concert: Michael Bolton and Kenny G. I had this friend who was all into Kenny G. back in like 1989, and took her for her birthday. That's above and beyond the call of duty for a friendship, I think.