[CrystalMethod]

I'd say either GitHub or DropBox. Only worry is if two people start working on the script at the same time out of dropbox, and when they both save, one person's work is lost. If you guys make separate copies of the script to work on sections, then paste it all together at the end, perhaps that'd work? I'm not totally sure, but that's my best guest. I've only ever scripted solo, never on a team.