IARU Monitoring System (Bandwacht)

SGO Meteor Radar

Space Weather: GOES X-Ray Flux

MUF 

VIRGO 

MMMonVHF

VHFDX.EU

ON4KST chat

N0UK EME chat

Geschichte UKW-Funk (History of VHF radio)

My friend DL8SCQ

For interests -  read the book Technical Handbook for Radio Monitoring: