I’ve added the ability to comment without logging in. You must answer a simple math question. (The problem is if you answer the question wrong you lose your comment! I’m looking for a better spam guard, but in the mean time, here you go.)
You can always comment while logged in as well. I think I’ve fixed the email problems.
Apparently, I have had some problems in the last few days–comments were not posting. I’ve fixed that again, so it should be working. I’m so sorry for the bother!