SIT

SIT is a free, open-source project that addresses these and other concerns in software that enables us to collaborate. It allows sporadically connected parties to continue collaborating seamlessly, over just about any digital transport (ranging from a P2P network to a USB drive). At its core, it's a very small tool that records every change as an immutable, additive-only set of files and allows this information to be displayed and operated on in a familiar way, though browser-based applications or the command line.