You can get a Disqus account AFAIK I think I have one, (I must, since I don't have twitter, FB etc..)
Then again I might have used my GMail, not sure.
Edit: Which brings me to question, how honest are those Google OAUTH 2.0 permissions that get displayed, isn't it up to the program to tell you or is actually Google showing you the permissions the application wants access to?
Same as FB and Twitter (although I think Twitter uses OAUTH 1.0, OpenID or something older than OAUTH 2.0)