Probably the Foxboro Hot Tubs, which was a Green Day side project. The 3 members of the band, plus longtime touring lead guitar player Jason White and keyboard player Jason Freese, under alias', played a short tour of 8 small venues. I caught them at a bar called One Eyed Jack's in New Orleans, and it was awesome. Though I did almost die about 6 times cos I was about 2 people back from the stage and Billie Joe Armstrong kept telling the audience "Flock to the stage! Come my children, gather 'round! Smother each other!" I'm a little guy (about 5'7", 120 lbs) in a sea of giants.
Runner up would have to be Carney, the musical group of Spider-Man: Turn Off the Dark star Reeve Carney and his brother Zane. It was an excellent show. They're a lesser known group, so everyone there was really into their music, which provided a great atmosphere. They were also very friendly ("We're not leaving this place until everyone comes by after the set and says hi!") and had great chemistry between them onstage. That was how I spent last Valentine's Day.