Well I'll add a vote for the anon posting as for my personal board, I like to create informal "discussion polls" to my customer base as to the direction I should take for certain things. I'm open to my registered users and any new people that happen by the site.
For me, I >feel< that having a "Guest" account that can post by using those >visual filters< (those graphics thingies that require you to enter the letters/numbers displayed on a garbled bitmap) as a way of entering a password as being the perfect solution to allowing anonymous posting.
In other words, if there's a way to programmatically have the >password be equal to the verification code< each time an anon user posts, that's a good way to 1) allow guest to post at your site and 2) filter out bots and (some) spammers...
Of course that would require the graphics library to generate those verification images and some programming code to somehow match the "login password at the time" to the same code displayed on the verifcation image.
I believe blogger does this also when allowing non-registered people to post on your blog...
-Will
PS - Thinking further, perhaps it's not even necessary to have the "password" match the verification code - the whole idea of the visual verification images is to provide a "pass" / "fail" kind of result - the post would be allowed (sans any password) as long as the visual verification succeeds.