Recent developments in the Innerpartysystem thread made me think about bands I've seen live who have later broken up or gone on hiatus.
I was fortunate enough to see Oasis live in September 2008 before Noel quit the band. Sad thing is the show was abruptly cut short because an asshole attacked Noel during the performance, cracking some of his ribs. Noel tried to push through and managed to get through 4-5 more songs before having to go to the hospital. I never got to hear Champagne Supernova live, and that makes me die inside.
I also saw Nine Inch Nails in November 2008. I don't know if the band is officially on hiatus, but Trent Reznor seems to be following other projects at the moment with no upcoming plans to resurrect the band.
Have you been fortunate to see any bands before they broke up or went on break?