Hmm I've pretty much seen every band I'd like to see live. I make it a point even if it involves traveling. But I suppose there are a couple that have slipped my list.
Muse for one. Had many an opportunity, Big Day Out being the most recent, but just passed it up, meh
RX Bandits, missed it while they were still together, but I think they are back, so technically it counts
and The Sounds, sure would be a fun 30 minute set.
Other then those I think my concert list is pretty complete. Seen all the big shows and many many small shows.