Sigbin is a web app that lets users store PGP-signed messages. Users paste a signed message into the box. If the signing key is on a key server and the signature is valid, it stores the signed message at /[signing_key_fingerprint]. If a message is already there, it overwrites it.
To get started, copy config-sample.py to config.py and edit it to put in your own values. Then:
$ virtualenv env
$ . env/bin/activate
(env) $ pip install -r requirements.txt
(env) $ python app.py
# when you're done
(env) $ deactivate