Recs.
Updated
SpecsUpdate
Pros
Pro Easy for non-technical users
CrashPlan is easy to install and manage, but still secure and featureful. It uses client-side Blowfish encryption. Just install it, select the directories you want tracked, and forget about it. Weekly email updates let you know that everything's working fine, and alert you when things go wrong.
Cons
Con Memory-hungry Java service
This application exemplifies many of the negative stereotypes of Java applications. Both the backend service and the front-end management utility are written in Java. The backend service can get pretty memory hungry if you have a lot of files in the tracked directories. It's also prone to occasionally segfaulting out of the blue. Luckily, CrashPlan notifies you if the service hasn't checked in for three consecutive days, so you're warned that there's a problem and it's a simple matter of restarting the service. Still, it would be nice if it were less resource hungry and more stable.