Well, for the sake of filling jgbrowning in, I'll explain the title of Nat20's supers book. Four-Color to Fantasy.
Old comics used a fairly poor-quality type of printing, using only four colors of ink - Cyan, Magenta, Yellow, and Black. By mixing any two of those colors, you can get a nice, bright palette, which is why so many old comics have very bright, flat colors. You'll also see a lot of computer art programs let you work in a mode called CMYK, which is just a higher-quality version of the old four-color printing method.
The term four-color, in comics circles, has come to be associated with old-fashioned, pulpy comics from the 30s and 40s. These comics were fairly simple and very intense, probably most recognizable by Superman. So, that covers the Four-Color part of the title.
Fantasy, well . . . fantasy is, for one thing, alliterative with four-color. Second, by saying four-color to fantasy, we're implying the great breadth of the product. Our superpowers book can be used for any setting or genre, from urban, 20th-century superheroes, to mystical, medieval fantasy settings. We could've made it 'Four-color to Fantasy, Stone Age to Space Opera', but that would've gotten a little long.
Basically, though, the title is meant to get across that it is completely adaptable, and useful for any gamer. Sadly, it seems, not as many people know what Four-Color means as we had thought.