Link
Plane-spotters:
http://www.planespotters.net/ EN
http://www.airplane-pictures.net/ EN
....................................................................................................................................................
Live ATC traffic:
http://www.flightradar24.com/ EN
....................................................................................................................................................
Military:
................................................................................................................
Other:
http://www.planesregister.com/ EN
http://www.libhomeradar.org/ EN
http://www.flightglobal.com/ EN
................................................................................................................
Photography:
http://www.cambridgeincolour.com/
................................................................................................................