Depends on the amount of data, music and video takes up a lot of space. For those I suggest setting up (or renting) a storage server and use rsync.
For your documents I suggest Dropbox
Dropbox allows you to sync your files online and across your computers automatically.
* 2GB of online storage for free, with up to 100GB available to paying customers.
* Sync files of any size or type.
* Sync Windows, Mac and Linux computers.
* Automatically syncs when new files or changes are detected.
* Work on files in your Dropbox even if you're offline. Your changes sync once your computer has an Internet connection again.
* Dropbox transfers will correctly resume where they left off if the connection drops.
* Efficient sync - only the pieces of a file that changed (not the whole file) are synced. This saves you time.
* Doesn't hog your Internet connection. You can manually set bandwidth limits.
Dropbox backs up your files online without you having to think about it.
* Automatic backup of your files.
* Undelete files and folders.
* Restore previous versions of your files.
* 30 days of undo history, with unlimited undo available as a paid option.