Backupify offers free lifetime backups of GMail, Flickr, Twitter*
Backupify is a dead-simple way to archive all those services from a central location. *Until January 31, 2010 they're offering free lifetime accounts to all new users.
They currently support seven services (which you can see above) and 6 more in beta: GMail, Hotmail, Facebook, Basecamp, FriendFeed, and Blogger. Support for YouTube, Tumblr, and XMarks will be added soon, as well as a way to archive any RSS feed you choose.
I'll admit, it's a bit of an ironic concept - backing up your cloud data in case a service shuts down onto another cloud service which could also shut down - but Backupify is elegantly simple to use and you certainly can't argue with the price right now.