Just saw Backstreet Boys this past summer.
Before that, Kanye West and Sugar Ray came to my university to play (Sugar Ray was amazing my second time seeing them, as usual, but Kanye's set was less than stellar). The year before that, we had Ludicris come to play.
When I was in high school, I had seen a lot of people live because of those grouped concerts: Mandy Moore (her 'Candy' days, it was weird), 98 degrees, Shaggy, Baha Men, Duran Duran, Sugar Ray, and some groups that I just want to forget. ^_^