keyplyr - 9:18 am on Feb 12, 2012 (gmt 0)
I black-list & white-list...
I white-list the 4 major SE bots w/ their assorted programs (UA filtered by verified IP range) and block the rest.
I UA black-list all *known* scrapers, downloaders, pdf makers, image grabbers/makers, and other file harvesting tools that stand lone or browser-side. Occasionally a new one comes along. These need to be manicured every few months for dead wood.
Server farms, clouds, hosting services, colos, etc are black-listed by IP range.
I also block every known IP range from China :)