Really similar to this list, which keeps track of individual gigs. This is just each band I've ever seen, whether an opening act, headliner, a small acoustic set, or whatever. Numbers in parentheses are how many times I've seen them.

• Passion Pit
• Muse (3)
• Ed Sheeran
• Enrique Iglesias
• Beirut
• Radiohead
• Young the Giant (3)
• Grouplove (2)
• Two Door Cinema Club
• Foster the People
• Cage the Elephant
• Death Cab for Cutie
• Mumford & Sons
• Kithkin
• Miyavi
• Flogging Molly
• Hepcat
• Fitz and the Tantrums
• Green Day
• The Bravery
• Jason Mraz (2)
• Lisa Hannigan
• Justin Furstenfeld
• Clint Black