I've not come across a plugin that does this, but there are existing tools you can use to achieve the same sort of thing.
Using Git and a private repo to store your template files and resources (CSS, JS). If you wanted to, you could also deploy these files to S3 pretty easily.
Using S3 or Rackspace within Craft to store your site's assets. This is a feature of Craft Pro, but allows you to skip the step of transferring files from a local source to S3. You can also take advantage of other AWS services like Cloudfront with this installed.
Task runners like Grunt or Gulp can also be configured to watch for new assets, template files and resources, and deploy them straight to S3. In theory, you could do the same with your database using the MYSQL dump package for Grunt, then watch for new files and sync. Or simply run a back-up task for your sites at the end of the day. This is highly configurable, but would require some work on your part to ensure it's running as expected.