I got to see the White Stripes play a tiny, run-down dive bar in Denver right before they really exploded on the national scene. I don't think there was 50 people in attendance. I'd never heard of them and when I saw a young man and woman get up from their barstools where they had been drinking beer and smoking cigarettes and take to the stage, I thought, "did the bass player call in sick or something?"
I was then completely blown away! They were just thunderous!
Saw Queens of the Stone Age play the same bar before they got big. I sure do miss that little bar.
I got to see QOTSA play before they got popular, and it was an incredible experience. They played lots of material off their first album - their best, IMO. The big downside was that it was so loud my ears were ringing for 3 days afterwards.