I currently have https://me.yahoo.com/admiral_memo.
The bad news is that Yahoo!'s version of OpenID isn't compatible with LiveJournal's version, so you can't yet use your Yahoo! name on here to make comments. (Believe me, I tried.) I will keep checking on this periodically to see if the status of this changes.
Check OpenID's site to see if you already have an OpenID that you weren't aware of.
Here is my tutorial of how to use an AOL account with LiveJournal. (Using this tutorial and the OpenID site I linked to, along with simple substitution, you should be able to get any OpenID-supported site to work with LiveJournal.)