I use one unique username/password for each site I visit. My browser will maintain this for the sites I'd like it to, and sites where security is important, I type it in manually.
In my opinion, developers are being selfish. They want one of their coding problems to go away (authentication and all it entails), at the expense of their users.
With openid, I have to open two accounts. One on the site, and another separate openid account to provide authentication. Problems? Well, it could be one, or the other. Does the brower help me? NO. Does it make me feel more secure? NO.
I used to contribute to stackoverflow, and then after having to deal with openid all those times, I STOPPED USING THE SITE.