You can also download some maps/scenarios from imagemodserver
http://imagemodserver.mine.nu/nick/games/starcraftmaps/
The SST = small squad tactics
Basically, it slows the game down, and makes each unit more important. You get resources quite slowly, so you typically only have a handful of units that you micromanage. You actually have to secure and hold territory in order to increase your resource production.
The dying of the light is the opposite, for those who like to just throw troops around. You get a million resources to start with, and 5 or 10 minutes to build before the onslaught reaches you.
(Note: you must select "use map settings" as the game type for those, or they'll be useless)