Dropbox lets you put your important files in a folder on your computer and those files will be automatically backed up and synced with all other computers you share the dropbox folder with. The free account permits up to 2 gb of storage, paid accounts allow higher storage levels.
The free account works great for important files, like your Keepass wallet and things like tax returns or other important documents. The service works seamlessly in the background and supports Windows, Mac, iPad and Linux! Recommended.