I am a dweeb about backup. I use FolderShare to synchronize files on my two main PCs, and I pay for Connected Backup for offsite storage. Connected is far too expensive, though--$279 a year for a measly 10GB of storage--and its user interface is awful. So I'm seriously thinking of switching over to Mozy (download), even though it's still in beta. There are three big reasons.
First of all, it starts out free: 2GB of storage costs nothing. Sixty dollars a year gets you 30GB. (Connected charges $800 a year for that.) That means that Mozy is an affordable solution for photo and video backup, while Connected is most definitely not.
Second, the interface is very straightforward. I was up and running with Mozy in a few minutes. Third, it's secure. Data is locked with a private key, to which there is no backdoor. (I have to take CEO Josh Coates's word on this, but it's a good policy.)
Advanced features that I haven't yet tried are the backup of open files, including Outlook (even Microsoft's own FolderShare won't do that), and sophisticated scheduling and bandwidth management (for example, you can tell the system to back up as much as it can between midnight and 5 a.m., then shut off or go into low-bandwidth mode during the rest of the day).
Mozy can't be used for sharing, since it limits users to five restore sessions per month (a session can be one file or an entire backup set). For online sharing, check out Box.net. But as a backup solution, Mozy is tops.
If Mozy sounds interesting to you, also check out Carbonite.