The CLSID List was originally started by Tony Klein as the BHO List, to catalog good and bad Internet Explorer Browser Helper Objects (BHOs). Over the years and across many different homes, it has expanded in scope to cover Toolbars, URLSearchHooks, and Explorer Bars, and has cemented its place as a truly invaluable resource to the online anti-malware community.
(Have you ever asked for malware-removal help at one of the many different HijackThis Log analysis forums? Your helper(s) likely used the list to help you out.)
A huge congratulations goes out to Tony Klein, miekiemoes, and all of the other contributors (and everyone who has submitted unknown items for investigation) for passing 60k!