This company claims to have combined tritium gas with tiny spheres of a phosphor gas which can be mixed into paint-like coatings. They claim 12+ years of lighting at $0.35 for an 8.5 x 11 sheet of paper's worth (or 0.25 Euros for an A4 sheet of paper's worth, to use more ecumenical units):

 

http://peswiki.com/index.php/Directory:MPK_Co%27s_Litroenergy

"Exit" signs (and perhaps others) have been available with tritium and a phosphor for years. Tritium is useful because it's low energy, beta only — there's no gamma. No batteries needed.

Thats cool. I wonder why they didn't have a picture of some one reading with white light. Make nice emergency lighting/escape route thingys.