Maybe mine aren't "Huge" but anyway. Most seen in the Dayton/Cincinnati area...
Collective soul @ Bogarts 1992/3 I cant quite remember the year right before Shine hit the radio, I was 12/13 at the time.
Mighty Mighty Bosstones a bunch of times/places before they had a radio hit
Dropkick Murphy's when they still had Mike Mccolgan as a singer, opening for the Bosstones @ Hara Arena
Dream Theater w/ Queensryche @ Hara Arena, at the time DT was still pretty obscure, at least to anyone my own age... Mike Portnoy Drum Clinic @ Hauer Music in 1992/3
White Zombie - Hara Arena, last bit of La Sexorcisto tours just before Astro Creep. Thanks to my middle school wrestling coach for taking me...
Queens of the Stone Age, starting in 1999. Cincinnati x2, Cleveland, and London before Songs for the deaf came out.
Tenacious D - Amsterdam 2001
Disturbed on their first Ozzfest
Incubus - Bogarts 1998/9 Sno-Core tour / Science was out at the time.
Black Label Society Sonic brew tour
Tool - Springfield ohio, some radio station rock festival 94/95, they were known but not big yet.
30 Seconds to Mars - They opened for Incubus before they had any radio hits
Also, I saw Clutch for the first time in 1998. I've seen them 15 or 20 times since, and I've never once gone to a Clutch show... They have opened for every damned rock band on earth.