[pbh]

There has been some academic work on this (CIDR'05), but I'm not sure if it has been used in practice.

http://ilpubs.stanford.edu/659/

[pavel_lishin]

Thanks, printed it off, will try to read on the train.

[InnocentB]

Sounds like a good use case for Instapaper :P

[protomyth]

Might not want the FBI to know he read the article if they come back for a "followup visit"