What's a band/artist that you've seen open (or support) for the headliner that you had previously not known about, but have come to really enjoy?

I find this to be tough, because not knowing a band's catalog makes it considerably more difficult to latch on to them.

I suppose it could be a separate question of what band that you didn't know wowed you, but I'll throw that in as well.

...

For me, I saw Bobby Bare Jr. open for Son Volt once, and while I thought he was OK, the album my friend bought turned out to be really good.

I also saw this band Everest open for Wilco and Neil Young. I thought they were pretty good, but never followed up to see if I liked their recordings.

OTOH, I liked the Bravery when they opened for Ash, but turned out to not like them so much once I gave them a listen.