LED matrix with 4017 ICs
You can try using two 4017s matrixed with a 555 timer for a 10 x 10.
But that doesn't stop there. You can cascade a string of 4017s either side to form any size matrix (20 x 20, 100 x 100, 5 x 20, 1 x 100, any size) as long as you have enough power source required to drive all the LEDs with powerful enough transistors. When you get to very large matrixes, you can create images or really cool psychedelic effects which are now popular in the entertainment field.
**broken link removed**
Jeff