Hi Fergie! Too Funny 
I’m curious; to what advantage is it to the website to have these guestbooks / blogs?
Okay, here’s my take on things. In most cases there is no advantage to the average site using it except to build a sense of community, much like the fine community the Prof has built here… thought you’de like that Professor.
But, from a strategic web marketers point of view it can go much deeper I think if used correctly.
Blogs especially get spammed alot by people who tend to add alot of “on-topic” comments in order to build backlinks. Depending on which software the blog runs on, a new page is created for each comment. So what if your blog had a .php include file on the bottom of each new page, and what if that .php include file contained links back to your own sites???
Get my drift?
In theory, you could be using the blog spammers efforts to better your own backlinks and thus your own rankings.
Does it work or make sense? You be the judge, I have my own ideas and I’ve probably said enough…