Wow, this is going to be long...I'm going to try to go in order as much as possible...but there has been a bunch so I might be wrong. And I'll also write which ones I met.
Bryan Adams - first concert
*NSync - 3 times, and went to one after-party
Blaque
98° - 2 times, had floor tickets first time, front row side of stage second time
CNote - met and had front row tickets
Jennifer Paige - met, had front row tickets, and got to watch her sound check
EYC - met and talked to for like 10 minutes, just us
No Authority - met and had floor tickets
Tatiana Ali (spelling?) - met and had floor tickets
BeWitched (spelling?) - floor tickets
Journey - saw them at least three times, don't remember for sure
Foreigner - saw once with Journey
REO Speedwagon - twice with Journey
Brooke Allison - front row side of stage
Baha Men - twice, front row side of stage both times
Debala Morgan (I know I spelt that wrong) - front row side of stage
Little Bow Wow
Dream
Kevin Eubanks (the guy who plays guitar on the Tonight Show with Jay Leno) - met him and his bandmates.
Beach Boys - met one of them...trying to remember his name. My best friend's grandma used to baby sit him...something Johnson I think.
Krystal (aka Krystal Harris) - twice, met and was front row first time, can't remember where we were second time
Sisqo - front row (we took other people's seats while they went up to meet Krystal, since we met her the day before we didn't go)
BSB - front row side of stage
Eminem
Xzibit (spelling??)
John Mayer
Maroon 5
No Doubt
Hanson - saw them in concert once, was front row, met them twice though...neither time was at that concert.
Aerosmith
I imagine I am forgetting some, but I can't think of anymore right now.