We've developed a system which involves the customer using a tool to create their own content, saved as XML. Predictably they are storing versions in a myriad of folders and renaming files, etc. And predictably they've already lost work at least once.
We're not responsible for the content they create but it would be nice to help them out. Are there any really easy systems we could recommend them... we don't want them using our VCS even if they could figure it out, as we'd then be getting support requests.
update We don't even need a client-server setup. It's about stopping them saving over their master version by accident, rather than providing a backup... we hold backups of the official versions but they work on them locally during an iteration and give us the newest version to include in releases.