I'm not even sure who all I've seen. What I remember:
Linkin Park w/ Alien Ant Farm - first concert around 2000
Around the same timeframe went to Johnny Dare's Birthday Bash (KC radio personality), which had Nickelback, Soil, Mudvayne, Three Doors Down (bleh), and many others I don't remember.
I think there was another rock concert I went to around this time, but I forget.
Saw ICP/Twiztid/Blaze/ABK 4 times from 2000-2004
Rob Zombie twice, once was with Anthrax, not sure on others
Apocalyptica with Dir en grey
Mushroomhead with Psychostick and Ventana - awesome show, seeing Ventana again in Feb.
And most recently Dir en grey with The Birthday Massacre.
Would love to see some of the shows vampko has seen tho. Particularly Girugamesh and High and Mighty Color (disbanded? *sadface*), but also Scandal and Miku.
Weird Al is pretty awesome too, but idk that I'd want to go to a concert.