Google will covert units for you. Try entering “7920 ft. to miles” into the search box. You can even use it as a calculator, for example try calculating the area of a 2.5 inch radius circle like this “pi*2.5^2”
Category: Web Site
TICalc.org has software for any TI graphing calculator, and some software that runs on your computer. Be sure to look thorugh the archives.
20q.net will guess just about any object that you can think of by asking you 20 yes/no questions.
For internet and media utilities I recommend AnalogX. Their tools are all free and very high quality.
Want to know what that song was that you heard on the radio? Yes.net can tell you. Just let it know when the song played and on what station and it will find the name of the song and even link you to the CD.