I suppose Pixies playing support to RHCP and Franz Ferdinand playing support to Scissor Sisters if second billing counts
if not then I have yet to see a really good support band in all the gigs I have been to... I was Ian Brown booed off stage supporting Manic Street Preachers...

I was in Tilburg, Holland last week or something. And Alter Bridge were playing. The openers were Enjoy Destroy from Hampshire, England and im sure i've never seen a better opening act before.
They put on a great show, and the crowd really warmed to them.
Rare to see.

two years ago i saw a John Butler Trio opening for a french singer. He totally stole the show and when the french guy invited him on stage for a duet at the end of the show, he pretty much got a standing ovation. stole the show!

In the spring of 2007 I went to see Peter Bjorn and John on tour promoting their Writer's Block album. I hadn't heard of either of the opening acts and in fact we showed up midway through the first opening act (assuming they were terrible).

Au Revoir Simone was quite the opposite! These Brooklyn girls and their keyboards were amazing. I instantly fell in love and look forward to seeing them again soon headlining.

After that came Fujiya and Miyagi, modern Krautrock if I have ever heard it. I can't wait until Lightbulbs hits the shelf as I've heard some of their new songs live and they're truly amazing.

So yeah, those two opening acts blew me away. Good thing PBJ was pretty good as well.

celebration opened for the smashing pumpkins when i saw them in asheville. hadn't heard of them before then, but they were a very pleasant surprise. i believe the lead singer contributed some vocals or something to return to cookie mountain.