Here's a thought. What songs would you want to hear from Billie Joe Armstrong solo? Obviously he would probably play a lot of Green Day songs, but it would be a good opportunity to play some rare tracks, or songs from his other bands/projects. I'm picturing him doing a mostly acoustic set, where he plays songs from all over the map, from:
These Paper Bullets
Pinhead Gunpowder
Foxboro Hot Tubs
The Network (an acoustic Roshambo anyone?)
Rodeo Queens
Billie Joe and Norah
Green Day unreleased tracks. (an acoustic Dreamcatcher anyone?)