Mozy (the backup client): damn close, but still no cigar...
Mozy's got what seems to be a nicely integrated Windows client (not sure how good their Mac client is) - their service seems simple enough, and you can't go wrong with two gigs free or unlimited (I've been questioning how much it takes before it becomes "abuse") for an extremely low $4.95/month.
However, this going back to my blog post a while ago about the end all backup solution, it still is missing one key thing. While the transfer is encrypted and the file contents are encrypted (optionally), the file and directory names are not. When I asked support, the response back was "how would you know what the file is then?" - to me, it's simple. You have an encryption key, why can't the filenames be encrypted as well using the same key, and decrypted on demand? I understand this complicates things then (how do you store junky filenames/etc...) - you'd most likely need a customized filesystem or some virtual layer between the two to do the translation. However, that would basically make Mozy the king in my book for Windows and I assume Macs (read: any level of savvy end-user who wants their data backed up.)
I would still be shopping though for one to use to backup my servers. Duplicity still seems like the best, as it will compress, encrypt, and do differential/incremental backups and due to the nature of how it works, will also mask the file contents so only the user can see them. Rsync.net has recently announced funding and support to help pump some life back into the project, which is promising. It needs native Windows support (which may be tricky... it needs a POSIX compliant backend) and proper S3 integration without patches or external libraries and hacks.
Of course, I was having fun developing my own little PHP interface to S3, which if possible I could then wind up creating my own tools; however, do I really trust my own coding for my critical data and extremely large filesizes? Because it's over HTTP, it's tricky (or maybe impossible) to byte-serve the data in PHP without precaching it into memory first... ah well.
Someone needs to create an efficient C-based one that can be compiled in Windows, OS X, and Linux. Any takers? I'll pay...