in reply to Remote OS Detection
This may not be the best approach, since they have legitimate access to the systems in question. See A practical approach for defeating Nmap OS-Fingerprinting.
IIRC there are other more subtly ways of achieving this sort of thing.
Also nmap may not be an option. Yesterday pankaj_it09 asked if it was possible to use Nmap::Parser without having nmap installed on the host system.
Conway's Game of Life
Perl regular expressions
My Magic 8-Ball™
Results (192 votes). Check out past polls.