General weather sites
Real-time weather data/Current conditions

The Weather Underground
Colorado State University Weather Lab
NCAR-RAP Real-time Weather Data
Interactive Weather Information Network (IWIN) - includes official warning statements and forecast discussions
weather.gov - NOAA/NWS site of current conditions, forecasts, warnings and advisories
WeatherTAP (subscription required)

Satellite Images
Forecast models
Tropical Meteorology
Storm Chasing
Blogs