Came across Bad Behaviour which is a plugin for WordPress which is a set of PHP scripts which prevents spambots from accessing your site by analyzing their actual HTTP requests and comparing them to profiles from known spambots. It goes far beyond User-Agent and Referer, however.
Also found out that Mark Jaquith’s blog showed some kind of stats in the footer.
Having not found any Stats plugin for BB, I wrote to him. He promptly responded with the function he is using to retrieve the number of spams blocked by BB.
And I decided to convert it into a plugin for WordPress.
Note that this IS NOT Bad Behavior plugin. It is a stats plugin for Bad Behavior. This plugin is useless if you do not have Bad Behavior installed