I have always been a little geekish... so I loved Miss Fit's idea of a pi bracelet.
I used the following gemstones:

1 = crystal quartz
2 = tiger eye
3 = turqouise
4 = amazonite
5 = white jade
6 = hematite
7 = gold stone
8 = red coral
9 = pearl

After finishing the bracelet I added a wire wrapped pi charm (It was my first try in wire wrapping - I know it's not good, and the wire is too fine...) to mark the position of the first digit.