DROPBOX stores autosaves................

[pipingguy]

FYI..........DROPBOX saves your file upon every autosave. So suppose you need to backtrack to find how/where/when you made an error, or you want to copy an object that you erased, just open the folder where the model is stored in your machine, right-click on the file and select 'view previous versions'. I have the paid-for version of DROPBOX, but I would be surprised if the free version doesn't offer this feature.

[Rich O Brien]

DropBox has this feature for quite some time.

If you want to do this locally without the cloud storage you can use Tortoise SVN to manage the version control.

I just use CloudUp or Save As Copy to keep a history of files