Mine is the Weather Underground:
http://www.wunderground.com/?MR=1

Lots of information, different views available, ability to zoom in and customize what you see and, important for us dial-up internet users, it all works well enough on slow connections.

Check this out, sixteen views of the storm:
http://www.wunderground.com/tropical/tracking/at200806_model.html?MR=1

Cool in my book.

I have no affiliations with this site. I just happen to like the ability to track storms and showers. Using this information I can often time jobs and activities to avoid the weather. Often down to the minute.