National Hurricane Center
This year the NHC has a new interactive map that gives information when you mouse over tropical features. This should prove to be a real time saver in what's shaping up as a busy season.
TCPOD (Tropical Cyclone Plan of the Day)
This is the daily CARCAH (Chief, Aerial Reconnaissance Coordination, All Hurricanes) product ordering air recon for the next day. Good to see who's going to be up. CARCAH is a small (3-person) office at NHC. Here's what it looks like.
Air Recon Data
More than anyone will ever need to know. Note that these are the raw observations and need to be combined with other data by the National Hurricane Center before they are safe for use in decisions regarding life and property.
NHC Advisory Archive
Good for tracking data or to see if an area had been affected on previous days.
53rd Weather Recon Site
Official web site for the Air Force Reserve "Hurricane Hunters" out of Biloxi, MS. Radio callsign is TEAL. It is likely that GULL either never existed or was used just briefly enough to create perpetual Internet folklore. TEAL is the one they use. Most comm is by satellite, but the front end can be heard on aero frequencies and the back end running patches through Air Force MARS on 13927 kHz.
NOAA Aircraft Operations Center
NOAA's WP-3D aircraft also do the "Hurricane Hunter" dropsonde missions inside the storms. They also operate a Gulfstream IV-SP which can drop instruments from high above hurricanes.
Hurricane tracking maps at Accuweather
Last year I got pretty good at tracking hurricanes just in Adobe Acrobat Pro, by layering line graphics over the PDF files of NHC's blank tracking maps from their site. This is kind of an expensive way to do it, though, if you don't already have the software for something else. Well, whatever. Anyway, this site has a lot of maps of smaller areas than the large "official" ones of entire oceans, allowing more detailed plotting as the hurricane nears landfall. You can get really Weather Channel on this stuff, though it's just as easy really to watch it on the Weather Channel.
U of W Tropical Cyclones
A comprehensive web page that pulls together links to a lot of satellite images, charts, and other hurricane products.
Weather Underground Tropical Page
Like the one above, only slicker and somewhat more "commercial" looking. Not saying this is good or bad, just saying it is. It also pulls together a lot of information.