Well, normally I buy at least one CD from every band, although there are exceptions if I really know I'm not going to like them. So here's last year:
Into Eternity: Didn't like them, their performance didn't change my mind.
Dreamscape: Bought the album, wasn't getting into it, thought the show was all right. then around January End of Silence "clicked" and I was overjoyed that I'd get another shot at seeing them this year. So that was a delayed reaction.
Tad Morose: Bought Modus Vivendi, it was okay, then the performance blew me away. Didn't sell me any more albums though, because I think Urban's voice isn't produced right on the albums. From interviews I've read, that's mainly his doing. He needs to just do it live and be happy with it. His voice really shines live. I'll buy the next Tad Morose album if his voice isn't overproduced.
Kamelot: Already a huge fan, performance met expectations, although I thought the song selection could have been better.
Savatage: Didn't like them, and then proceeded to get blown away by their performance. I wasn't even planning to stay after Kamelot, but now I'm glad I did! So you could say that was a discovery.
Adagio: Thought the first album was all right, performance was all right too.
Wuthering Heights: Bought the first album in 2000, hated it. Bought the third album in preparation for the show, thought it was a major leap forward. The performance was even better.
Brainstorm: Bought Soul Temptation, thought it was okay. Performance was incredible. That performance sold me Liquid Monster and now I can be counted as a Brainstorm fan. So that's discovery #2. Hoping Symphorce does it for me this year. I haven't been all that impressed with Twice Second, but a kick ass performance will cause me to pick up Godspeed.
Pain of Salvation: Bought One Hour By the Concrete Lake in 2000, hated it, used their set for CD buying time. Caught the last 15 minutes, still wasn't impressed.
Edguy: Awesome, awesome, awesome. That's all I can say.