I've been using phpMyID as my OpenID provider, but its author has announced that it's now deprecated. It doesn't support OpenID 2.0.
I don't like depending on a third-party OpenID provider. I want to run my own provider on my own server. So, I'm looking for a provider that is open source, secure, and easy to set up for a single user. I'd rather not have to set up a database for it. The language it's written in isn't a major factor, as long as it's easy to set up on Linux+Apache.