for bearman: Aphex Twin.
I'm grateful I got to at least see that one...
It's hard to think of any current artists I haven't seen but still perform. I guess I'd like to see the current Misfits thing. Neil Young. The House of Love (whichever lineup Guy Chadwick is putting together). David Byrne. Hole (sounds like the classic lineup is rehearsing).
Bands I wish I could see if I could time travel: Joy Division, Husker Du, the Doors, Bryan Jones-era Stones, Motorhead (no Sleep Til Hammersmith era), The B-52's with Ricky Wilson (Wild Planet era), Pylon, the Gun Club, the Cramps, Minor Threat, Black Flag w/Chuck Biscuits on drums, Circle Jerks w/Chuck Biscuits or Lucky Lehrer, the Jam, Bowie circa Station to Station, the Who circa Tommy, Big Black, the Smiths, the Fall.
Bands I'm glad that I saw while I could: The Stooges, Red House Painters (when Gorden Mack was still on guitar), Cocteau Twins, Galaxie 500, Heatmiser, Elliott Smith, Nirvana, Lou Reed, Material Issue, Lush, INXS, the Germs (okay, Darby wasn't there, but that show was still insane and incredible), the Buzzcocks, Beastie Boys, the Ramones, George Michael, RUN DMC, Grant Hart, AC/DC (though I guess a version of them will be touring soon), Rush, Soft Cell.