planespotters.ch is on Instagram, Facebook and Twitter:
https://www.instagram.com/planespotters.ch
https://www.facebook.com/planespottersch
https://twitter.com/planespottersch

Online Spotting Database:
http://www.spottinglog.com

Informations for Spotters:
Aircraft Registration Database Lookup
http://www.airframes.org/
Aircraft Tail Codes
http://www.flugzeuginfo.net/table_tailcodes_country_dt.php?sort=tailcodeasc
Aircraft Type Designators
http://www.icao.int/publications/DOC8643/Pages/default.aspx
Airline / Air Operator with Callsign
http://www.flugzeuginfo.net/table_airlinecodes_airline_en.php
Civil Aircraft OnLine Registers
http://www.avcodes.co.uk/reglinks.asp?type=Official
Airlines, airports, fleet data and flights
https://data.freshaviation.co.uk

Image Databases:
Aviation Photos & Live Flight Tracking
http://www.flightaware.com
Aviation Photos, Airline Fleets & more
http://www.planespotters.net
Aviation Photos, mainly LSZB
http://febebernairnewsaboutus.blogspot.ch
Fellow Enthusiasts:
Fotogalerie rund um Airshows & die Aviatik
http://www.swiss-wings.ch/
Aviation Photographer
http://www.markis-aviaweb.ch/
Aviation Photographer
http://www.felix-gallery.ch/m3/
Aviation Photographer
http://www.eschki.ch
Aviation Videos
http://www.matthiashaenni.com
… und seine Facebook-Seite
https://www.facebook.com/MatthiasHaennisWebsite
Swiss Air Force History
http://old.hermannkeist.ch/index.php

Miscellaneous:
pilot career, flying simulation, airports, airplanes and model planes
http://www.kehdiaviation.com