Browser Detection of Website Statistics Services
An anonymous reader submits "David Naylor has reviewed the browser recognition capabilities of seven free website statistics services. Among other things, he kills the myth that many Opera users go unaccounted for in website statistics because of the default UA spoofing. Furthermore, he shows that the quality of browser recognition ranges from absolutely abysmal to near perfect."
The same but with web server log analyzers. For example I suspect Webalizer for not being accurate concerning user agents.