I worked on a spiders xml list a while back, which is now being taken care by Mosh over at vB.com, which has 500 spiders, he's doing a great job with it. xenForo could have a log on the admin control panel so we can view statistics of spiders, which spiders are browsing, now and on the last X days, etc. I like being able to tell on the who's online which guests are lurking and which are spiders also. Just brainstorming, xen could have a centralized spiders database, which all xen instances use for this instead of each forum having to update it's xml file. Just a thought.