Terrace is the most popular 2v2 map and 1v1 map that is WW related (WW means westwood, which means an original map of the game)
Forest Fires is the most popular 3v3/4v4 map that is WW related.
Then you get into various other maps like a River Runs Near, Night of the Mutants, and Tunnel Training. I wouldn't recommend playing these until you get terrace down first, the reason is because these are rarely if ever played much anymore with the exception of them being just pure fun matches.
Conflict - most popular mod ranging in maps that serve 2v2, 3v3, or 4v4 matches. Some versions are speeded as well, and by this I mean some units move faster or are cheaper, etc.
BBG (Big Bluntz Green) - second most popular legitimate mod and I say legitimate is because it isn't surrounded by visceroids, versions from 2v2, 3v3, and 4v4
Green Moon - Very old but well balanced mod map 2v2
Next up comes the awkward mods
Visceroid maps - These are extremely popular, and seems to be at least 1 game up at all times. What happens is your base starts out surrounded by concrete, and generally speaking you need to expand to tiberium around you by killing visceroids and making more concrete to the tiberium. This involves patience, and generally RPG's for GDI, or rocket infantry for nod - after you of course expand, you can use titans to easily take care of the visceroids without damaging the walls.
The other maps kind of vary between grays and nodrescue's vast array of mod maps, all of which are fun - but generally very long games.
Edited by jZampageX, 03 March 2010 - 01:42 AM.