I did some reading when I happened across this link for a new type of light-emitting material that will glow for 12 years, with no batteries or outside power.  It’s like the glow-in-the-dark materials that glow when you hold them under a light for a while, except you don’t need to hold this new material under a light, and it keeps glowing for 12 years.  The technology is currently patent pending, although I’ve got some questions as to exactly HOW this technology works. . . .There’s a similar effect that can be created using some mildly radioactive materials (Tritium), although these materials are highly regulated by the US government, and can’t be used in just anything.  (Apparently its considered a “frivolous” use of nuclear materials.  So you couldn’t make a glowing keychain out of the stuff because it’s not allowed.  It’s possible, and its been done overseas, but not in the US.)  I like the idea of a new non-nuclear 12-year glowing light paint/material, but I’m skeptical as to the technology used to make it happen.

http://www.treehugger.com/files/2007/12/new_light_glows.php?q