Games and puzzles of use could be found here
or here (Primary mainly I think)
Two useful weblinks for teaching specific skills and topics:
1. http://www.mathcentre.ac.uk/staff.php
2. http://www.calculus-help.com/index.html

Infoplease’s Online Calculator http://www.infoplease.com/math/calculator.html
Universal Currency Converter http://www.xe.com/ucc/
Start each lesson with a quick activity here!

A site with great Mathematics videos
Great interactive materials site with lots of links http://www.interactivemaths.net/