Propagation & Weather
Space Weather by SolarHam.net from VE3EN
Great collection of solar tools and information (lots of photos) to help hams fully understand current conditions.
NOAA Space Weather Prediction Page
The go-to guys for what’s in space http://www.swpc.noaa.gov/communities/radio-communications
N0NBH HF Propagation and Solar Data Tools
A fantastic collection of useful, real-time solar & propagation tools you can use, and gadgets to add to your ham website.
Worldwide Lightning Location Network
University of Washington @ Seattle operates this worldwide network of 40 VLF sensors, with excellent displays on their website -- updated every 10 minutes.