Or...How I would run an online backup service completely unrelated to Tarsnap, with different goals, different priorities, and different ideals.
Yep, I think this is basically the problem with this post, it's Dropbox with an open source client and maybe that is what he doesn't want it to be.
If you think Tarsnap is Dropbox with an open source client (but marketed differently), a) you do not understand the engineering reality of Tarsnap (or you have a very... curious understanding of Dropbox) and b) Colin, please note that your marketing is creating fans who think that Tarsnap is Dropbox with an open source client.
How about Dropbox + TrueCrypt, except easier to automate and much cheaper beyond Dropbox's free tier, in exchange for taking the risk on a one-person business?
You realise that Dropbox isn't a backup system, right?
I have a backup file there, so can confirm it does work for that purpose.
Um, no.
Delete that file on one device, it is gone from all that share it.
Dropbox preserves history of the file even after file was deleted.
Especially with Packrat feature.
https://www.dropbox.com/help/11/en