What live cds do you carry around?

TPC writes: "I recently acquired a small cd case that fits 12 CDs. I figured that it would be useful to always carry around a few cds to use when helping others with computer issues, or in case something goes wrong with my own computer. But I'm having a hard time deciding what CDs to pick, there are probably many hidden gems out there. I'm sure I'm not the first person with this idea, so I ask you: What 12 live (and otherwise) CDs would you carry around?"