I only backup some documents and scans folders right now, so I don't use a lot of space.
As a result, I just use a combination of Windows Live Skydrive, Gladinet Free (to mount it) and a task-scheduled robocopy.
There's enough space left (they give you 25GB) I could probably backup all of my pictures as well.
edit: Actually, for some reason, the performance of Gladinet is very slow and robocopy didn't want to schedule in Win7. So I started trying out the Mozy Home's free 2GB last night. Super easy, seemed to work well.