I used to wait for AeroFS to mature, but now I just use encfs on Dropbox and that's my syncing problem solved. As for backups, I'm currently using SpiderOak. I haven't found anything cheaper (on the order of Glacier) that supports encrypted backups. Hopefully there will be a tool like duplicity (which, unfortunately, I've had bad luck with) for Glacier.

I tried to use Duplicity a few times with WebDAV (for box.com), and it kept freezing, becoming unable to resume the transfer, unable to see that I have files on the share even when I managed to upload all the files with the desktop client, and various other bugs. It's not as robust as I'd like, sadly.

I use duplicity with my tonido home server for my backups. Tonido is also a webdav server. Duplicity works well With Tonido.