Sign up for a Dropbox account and get 2 gig of free online space (2.25 gig if you click this dropbox link). You get 50 gigabytes if you sign up for $9.99 per month. WordPress has some super dropbox plugins that integrate with this external storage system.
If you recommend a friend, you get an extra 250MB of storage per referral – up to a limit of 8 gig.