Dropbox tries to simplify file syncing

Dropbox is a new file sync and backup service for Mac and Windows that is currently in beta.  It creates a new folder on your computer that you can drop files into and the Dropbox software will automatically copy your files to their servers.  You can then use the service to sync the files across multiple computers or to share them with friends.  If you make changes to a file, Dropbox will keep track of the changes and allow you to “roll back” the file to an earlier backup.  If you’re away from your computer, you can access your files (and revisions) through their website.  The service is presently free, but you are limited to 2GB.

Dropbox website