This is probably the best radar, with storm track, the ability to zoom in, and a huge variety of other features. For advanced radar types on the Weather Underground site, hover your mouse over the "Advanced Radar Types" image that is located along the left edge of the radar image.
Weather Underground's WunderMap - Interactive Radar
Weather Underground's WunderMap is one of the best weather tools available. It allows you to view radar data combined with weather station and satellite data. You can choose what you want on the map. You can zoom in as close as your house or as far away as you want. They have a large amount of other features available to add to the map.
Weather.com Interactive Radar
This has few features compared to Weather Underground's radar, but you can also zoom in as close as you want like Weather Underground's WunderMap.
Regional NEXRAD Radar:
Get a regional view of radars from many locations.
National Weather Service Radar
This is another good site for radar. Unlike the Weather Underground site, you can pause the radar on this one. It uses Java for loops on this site, so you will need it to use the loops. There is also regional views.
This site is good to use to view an entire regions worth of radar data. If you want to see a large part of the storm in one radar as it makes landfall, this is a great radar to do it with. The radar loops on this site are also longer which is a nice feature to use.
Bahamas - Not available as of posting this. When available, it is difficult to view because it uses the Quicktime plugin. It does not seem to frequently update. Using the radar can be difficult due to the Quicktime plugin that is used. For me, it cuts off most of the radar. I have to actually download the .mov file to view it. Click here to download the radar .mov file. (To play it in your browser, click the link. The best way might be to download the file by right clicking the link and saving the file. Then open it where you saved it.) Then you can also see the time on the radar.
Curacao (covering Aruba and Bonaire): Image | Loop
Dominican Republic - Not available as of posting this. (Try here, but check the times: Possible New Page or Older Page)
Guantanamo Bay: NOAA (Sometimes outdated)
Jamaica: 180km, 480km (Radar imagery often not available. Make sure the time is current when it is available.)
Martinique (Wider View)
On that page: "Précédente | Animation | Arrêt | Suivante" -> "Previous | Animation | Stop | Next"
Panama Canal, Panama: Image | Loop
Puerto Rico: Weather Underground Long Range | NOAA Long Range
St. Maarten (Saint Martin): Image | Loop
Trinidad and Tobago