Clamshell is an OpenID server implementation I have developed as part of ongoing work at building my own wiki software.

It's very simple and is really just a re-modularization and extension of the phpMyID single-user OpenID software.

But it tests out OK as a compliant implementation of the OpenID 1.1 spec and may prove useful to others. (For those who don't know what OpenID is, think of a decentralized implementation of the Passport or Liberty single-sign on systems.)

Download a copy here