This is one cool calculator:
http://www.metacalc.com/#/large/

From From the The Standards Site Interactive Teaching Programs website: Decimal Number Line is an interactive teaching program which allows you to select an interval from a given number line and show that interval as a second number line divided into ten equal parts but on a bigger scale...

The program is available in a number of formats including a Windows exe file, a Macintosh file and as a flash program. Supporting documentation is also available. Web address: http://tinyurl.com/325zyx

http://clem.mscd.edu/~talmanl/MTH1410F07/Pictures_091007/
From the website created by Lou Talman: In each of the following pictures, which curve is the original function, and which curve is the derivative?

http://www.peterrussell.com/Odds/WorldClock.php
The World Clock website has continuously updated information about the world such as the world population, number of births, number of deaths, number of cars and the number of barrels of oil produced. It is a wonderful discussion starter for a number of maths topics including time series data and rates of change (gradient).