Silverchair was my first ever concert and Magic Dirt were supporting! In 1997. My ears have been ringing ever since (literally tinnitus is annoying as hell).
Uhmm... heaps of Aussie bands, like Grinspoon, Spiderbait, Superjesus, Jebediah, The Living End, Frenzal Rhomb, etc etc etc. I was on stage with The Living End followed by TISM at Homebake in ... 1998?
Fear Factory twice
Pantera
Nine Inch Nails twice
Incubus ..twice? thrice, maybe?
Deftones twice, last year and I met them in 1999! Best Vans Warped Tour EVER!
Slayer and Machine Head
Slipknot (hahahahahahaha)
Foo Fighters about four times
Green Day three times
System of a Down (twice, I think?)
The Used (I got free tix and backstage to the meet and greet -- I didn't even know who they were hahaha

)
Last year at Soundwave I saw Suicidal Tendencies, Parkway Drive, Blindspott, The Bronx, Behind Crimson Eyes, Hatebreed (hahaha), Flyleaf, Thrice, etc
Probably a lot of other bands, I just can't think off the top of my head...
I have to agree with Nikki, Tool was the best show EVER. I went both times they came out in 2002, and missed out last year...
Most recent concert was Parkway Drive in October which was awesome expect for getting punched in the face

, and next concert is Soundwave TOMORROW!!! I get to see Alexisonfire, Killswitch Engage, As I Lay Dying, From Autumn To Ashes, oh yeah and Incubus and The Offspring (blech).
Bands I most want to see and haven't are A Perfect Circle and Faith No More (Won't hold my breath on the latter hahaha).