Perfect numbers
This is a wonderful site with a lot to do. It starts with simple indices and factorising numbers, takes you back to Ancient Greece and gets more and more involved. There is a couple of hours work (you don't have to do it all at once), but by the end you will have more appreciation of perfect numbers.

Fibonacci
Do you remember the sequence
1 1 2 3 5 8 13 21………
where each number is the sum of the previous two?
Well this sequence pops up in maths and in nature all the time in the most unexpected places.
There is lots to look at and do on this site. You can just pick the bits you are interested in. Try out the interactive sunflowers.

History of Maths
This is a whole site about the history of maths and mathematicians. There is far too much for any one person to take in, but why don't you have a look and find out about mathematicians you have heard of. You have heard of a few - Pythagoras, Newton, Fibonacci maybe even Archimedes and Einstein.
Or you could find a mathematician with the same birthday as you.

Fractals
There is a relatively new area of maths which involves drawing infinitely detailed patterns on the computer using a simple mathematical equations. No real maths for you to do here, just enjoy creating the images.