incrediBILL - 12:57 am on Jul 6, 2010 (gmt 0)
I haven't been paying attention but this one is nasty
I've seen UAs of "Casper Bot Search", "rk q kangen" and "MaMa CaSpEr"
They're all trying to find ways to upload files to my site such as:
I would block anything with "/casper/" in the query string as an added measure of protection.