I like OpenID although I think it’s more complex than most people can handle — and that’s a big hurdle. OpenID gives visitors to your blog or web site a chance to log in (create an account on your site) using their login information from a participating OpenID web site (like gmail). In other words, they don’t have to create a separate account at your blog – they just reuse their Yahoo (or gmail or other) account. In theory this should make it easier to remember account names and passwords because you just use one account to log in at many sites.Ever since OpenID was announced (2005) I’ve loved the idea. There are OpenID providers, and then there are other sites that allow users to utilize OpenID for the creation of accounts.
Recently I became my own private OpenID provider. I did this using phpMyID (see below). I created a private page that sits on my personal web site, and when I’m at a site that uses OpenID I supply the URL of this private page, type my name and password, and bingo I’m logged in at the third-party site. I used phpmyID, which is listed in the OpenID directory.
On the utilization side, when DiSo Project created an OpenID plugin for WordPress, I immediately installed it on my blog. And it works. Lets you log in at my blog using your Yahoo or gmail (or other OpenID provider)  information without creating a new account.
 From OpenID.net the following description:
OpenID eliminates the need for multiple usernames across different websites, simplifying your online experience
You get to choose the OpenID Provider that best meets your needs and most importantly that you trust. At the same time, your OpenID can stay with you, no matter which Provider you move to. And best of all, the OpenID technology is not proprietary and is completely free.
 AOL, Google, MySpace, Yahoo!, Blogger, Flickr, LiveDoor, LiveJournal, Orange, SmugMug, Technorati, Vox, WordPress.com … and probably some others. See the OpenID site for a current list.
 Do you know your gmail Google OpenID? You can find it with just a few clicks.
 If you have a WordPress.com blog, (like let’s say you have a blog called myblogname.wordpress.com) you use the URL http://myblogname.wordpress.com/ as your OpenID. You will have to log in at WordPress.com in order to validate your password, but once you’ve done that, you can log in using this URL.