I'm using git-annex-assistant right now and while it is really nice and promises to replace dropbox for me, it would still use a lot more loving. There seem to be some weird states that you can easily get it into (I've had issues with the files syncing properly but the webapp claiming that the syncing was failing (or rather, that item is colored red, has an "!", and doesn't say anything else), it does not handle very large numbers of small files well (something git by itself does well),and a few other assorted problems).

Looks like the developer is going to be giving it more loving full time for the next year -- https://campaign.joeyh.name/ almost funded.

Yup! Joey is dedicated as hell which makes me really optimistic about the future of git annex.