Some interesting web links

http://www.cecm.sfu.ca/projects/ISC/   This is to an inverse symbolic calculator.  Why would you like that?  It lets you start with a number and find an interesting equation which creates it.   For example take a date, like July 4, 1776.  Convert it to a 'simple' number like 7.41776  or 0.7041776 and this will give you a function to create that number.  

http://www.seanet.com/~ksbrown/   A good general math site for looking up those forgotten equations, like how to calculate the odds against a royal straight flush.

http://www.cut-the-knot.com/   Interactive math puzzles.

http://www.geom.umn.edu/software/download/   Downloadable geometry software

http://www.mcs.surrey.ac.uk/Personal/R.Knott/Fibonacci/phimaths.html   This is a reference to the number phi and its interesting properties.

Capturing some of the flavor and features of the number 1.618033988...  The Golden Ratio