OpenID is a burgeoning standard for identifying and authenticating yourself on the web. You do this by identifying yourself not with a standard username and password, but with a URL. This URL points to a web page that verifies that you are, in fact, you.
A number of third-party sites offer OpenID URLs to their users, including LiveJournal, AOL, and Technorati. But some people do not like to be beholden to third parties for something that may turn out to be a central part of their online identity, and they’d rather host their own.
An easy way to do that is with an open source PHP identity server called phpMyID.