WeatherMan and WeatherManX

Download weather information from the National Weather Server right to your Macintosh. Unlimited number of cities, current conditions, forecasts, severe weather alerts, Nexrad radar and much more.

Price: $10 after 30 day trial.

WeatherMenu

For those running OS X, full weather information in the menu bar:
Price: Free. (Will be updated but not officially supported)

CIDTracker and CIDTrackerX

Decode Caller ID information from a CID capable modem. Keep call logs and run AppleScripts when a call comes in. Currently in public beta testing.

Price when in final release: $10 after 30 day trial.

WeatherTracker

Grab data from home weather stations like Davis Vantage Pro, Oregon Scientific WMR968 and WM918, LaCrosse 2310 (any 2300 series I think). Currently in public beta testing.

Price when in final release: $TBD (Probably $50).