I'll put some of my smaller tools to the contrib github.
For now it contains ssh-sign, which allows to use your
existing SSH hostkeys to encrypt/decrypt (RSA)
or sign (RSA and DSA) files. You can verify the signed
files against your ~/.ssh/known_hosts after fetching.
This for instance allows to add integrity to pure HTTP
downloads if you have the SSH hostkey handy since you once
ssh'ed to that host.