Dropbox + SVN Repository

Using a source-control system is a useful practice even on solo non-trivial projects. Even though you don't need to worry so much about the collaborative aspects, you still need to version your code so that you can roll-back in case you've done some bad refactoring or have taken a wrong design path.

Luckily, setting up a local SVN Server on a Windows machine is incredibly easy, especially if using the free VirtualSVN package. You can install, configure and connect to a repository in under a minute!

Since your SVN repository is stored on your local machine however, you still need to protect yourself against hardware malfunction or accidental data loss. Simplest way to do this is to configure the VirtualSVN server to place the repository root folder in your Dropbox target folder.

You can then use your favourite IDE with an SVN plugin to version your code, create branches, etc, whilst everything is transparently stored in your SVN and replicated to your online Dropbox account. Sweet!