G3SEK Ham Software Lots of ham-radio design software (antennas, rf...) and more
Ralf Kloth's DL4TA collected many interesting information on packet and radio
QSL.net Al Waller, K3TKJ, runs the QSL.net with many HAM-homepages
Hamradio-Portal Andre und Carsten offer HAM specific info
QRZ.com International callsign directory
mods.dk modifications Collection of modification hints for radios