I'm a Jungle Drive user, and while I don't pretend to be an "average" user, it was very easy to install. I'm not sure if setting up an Amazon S3 account and then putting the key into Jungle Drive would be too technical for the average user, maybe it would. Overall I've been very happy with Jungle Drive so far, and the $20 one time charge is pretty nice, particularly since I can use that on as many machines as I want with one Amazon account.

How does that compare with ZumoDrive?

--Disclosure - not currently a user of ZumoDrive