UNKNOWN: Combat sites. Can be found with ANY PROBE TYPE.
GRAVIMETRIC: Hidden asteroid belts
MAGNETOMETRIC: Archaeology/Salvage profession sites
RADAR: Hacking profession sites
LADAR: Gas Cloud sites min cal ama

=== NPC DAMAGE TYPES ===
Angel - All - mostly Explosive/Kinetic
Amarr Navy - EM/Thermal
Blood - EM/Thermal
Caldary Navy - Kinetic/Thermal
Gallente - Kinetic/Thermal
Gurista - Kinetic/Thermal
Khanid - EM/Thermal
Maru - EM/Thermal
Mercenary - EM/Thermal/ (Kinetic for missles)
Mordus - Kinetic/Thermal
Odamian - Kin/therm
Rogue Pirate - EM/Explosive/Kinetic
Sansha - EM/Thermal
Serpentis - Kinetic/Thermal

http://eve.battleclinic.com/killboard/combat_record.php?type=corp&name=Norwegian+Dark+Forces
http://eve-survival.org/wikka.php?wakka=PirateRadio3