Stylesheets demonstrating the use of GSS:
Mapping the world in the style of classic computer game Warcraft II:
http://cartagen.org/find/london?gss=http://unterbahn.com/cartagen/warcraft.gss
Stylesheet: http://unterbahn.com/cartagen/warcraft.gss

This map was made with Cartagen, but goes further than basic stylesheeting. Still of interest: http://newsflow.cartagen.org/
Stylesheet: http://newsflow.cartagen.org/style.gss

Labeling in different languages based on URL parameter:
http://cartagen.org/find/brussels?gss=http://unterbahn.com/cartagen/localization.gss&language=fr
http://cartagen.org/find/brussels?gss=http://unterbahn.com/cartagen/localization.gss&language=nl
Stylesheet: http://unterbahn.com/cartagen/localization.gss

Coloring by author name:
http://cartagen.org/find/london?gss=http://unterbahn.com/cartagen/authors.gss
Stylesheet: http://unterbahn.com/cartagen/authors.gss

Using tagged street widths to
http://cartagen.org?gss=http://unterbahn.com/cartagen/width.gss
Stylesheet: http://unterbahn.com/cartagen/width.gss

Stylesheet: http://unterbahn.com/cartagen/natalie.gss
(you have to pan around a bit to get this one to render in)

Use patterns to display stylized maps:
http://mushroommap.com?gss=/styles/ben/styles.gss
Stylesheet: http://cartagen.org/styles/ben/styles.gss