Masq2 supports OpenID 2.0 and supports SReg, AX (fetch and store requests) and PAPE as well as some custom additions like multi-factor authentication using a yubikey

Provides a more HTTPish API around the ruby-openid2 library

Ruby OpenID Test Server (ROTS) provides a basic OpenID server made in top of the Rack gem. With this small server, you can make dummy OpenID request for testing purposes, the success of the response will depend on a parameter given on the URL of the authentication request.