The conditions that make for exciting amateur radio are due to interactions of many phenomena, both intrinsic and extraneous to the planet. This page contains links to information concerning solar activity and it's affect on radio wave propagation. The conditions and activity levels of solar activity, the planet's geomagnetic field, and auroral activity is known as "Space Weather."
Space Physics Interactive Data Resource (SPIDR)
Rice University's Space Weather Page
NOAA's Solar-Terrestrial Physics Page
NASA - Exploring the Earth's Magnetosphere
Recent Solar and Geomagnetic Data
Space Environment Center, Today's Space Weather
ARRL Propagation Forecast Bulletins
Last 25 WWV Solar Flux reports
Near-Real-Time E-Layer Critical Frequency Map
Geophysical Institute Auroral Forecast Maps
Auroral Activity from NOAA/TIROS