Had the TruGlo TFO (tritium fiber-optic) sights on a G27. I liked them. Very bright under all light conditions (from sunlight to pitch black). Only drawback is that they are big bright dots, maybe not as good for really precision shooting.
http://www.truglo.com/content/products/firearm/handgun_sights/handgun_sights.asp
http://www.truglo.com/content/products/firearm/handgun_sights/handgun_sights.asp
