WeatherBug
WeatherBug is a piece of software for Microsoft Windows which displays the current temperature in the windows status bar.
Given the trivial primary function of the tool (finding a current weather report is a trivial matter for a user with the "always on" internet connection required for Weatherbug to work) coupled with the large amount of advertising and difficulty in uninstalling the software led to the definiotion of at least the earlier versiond of WeatherBug as adware, in the pejorative sense of "software whose true primary purpose is to serve as a vector for advertising". Notable adware/spyware removal utilities, such as Symantec AntiVirus, recognize and remove WeatherBug.