SuperLuminova is the brand name for strontium aluminate-based material that provides the long-lived glow often seen on divers' watches. Previous lume was based on zinc sulphide; this is easily ten times better.
Check out this chart:
(Image credit: http://www.rctritec.com/)
There are multiple grades and colors, and brightness can be increased by applying multiple layers of lume. Lum-Tec uses six layers, and their watches are superb.
From their forum, how they do it. Base layer of super white TiO2, then lots and lots of SL: (click for fullsize)
Here's a PR picture from the Lum-Tec C1, which uses six layers of superluminova:
Note that Lumibrite is Seiko's name for SuperLuminova, same formula. As you can see, it's awesome bright! I hope to measure this soon.