These 'glow in the dark' key rings are pretty cool!  They dont need any batteries and they keep glowing for 10 years!

The Glowring is made up of a pressurised laser sealed glass tube. 

This Gaseous Tritium Light Source (GTLS) emits a really bright neon glow in the dark.  You can even see it from upto 20 feet away.

It's pretty cheap (approx $18) and I think its a pretty nifty 'techsnack'!