I'm hoping someone does a cloud service for note syncing using a code control back-end. I would really love to be able to look at the changes and rollback a change or delete.
They also have pretty snazzy Android and iOS apps for OneNote, although IIRC the mobile apps require an Office 365 subscription.
Out of everything that comes out of Redmond, OneNote is definitely one of the best consumer products.
And it's all free! Though obviously you could use paid Dropbox and Bitbucket/GitHub accounts as well.
Until fairly recently I used OmniFocus and Evernote, in conjunction with their mobile offerings, but I don't think I'll be looking back anytime soon.
That enables you to display the history of a file by handling the output of <git log $file> without confusing the user too much (it's linear, just like his changes), you get full reverts, syncing (push if you have internet), multi-device-support (clone). You'd even be independent from the actual repository host with the app itself, since git doesn't care about it's remote location.
It sounds like a pretty good idea just from thinking about it for a minute.
I did lose one Google doc once (a drawing). About a year or so later it turned up again, really odd.