I'll probably get Warcraft 3 soon, it's easily my most played game of all time, so it deserves a second payment from me.
Good maps that I remember:
Parasite. Everybody's on a ship and one guy is secretly an alien. Part of a mini-genre of The Thing-styled games and by far the best. I was godlike at this game, and won basically every round.
Zerg infestation. Everybody's at a terran base and one guy is secretly a zerg. Second best of The Thing style games.
Night of the Dead 2. Everybody's in a city and there are zombies. Lots of fun.
Night of the Dead Aftermath. Everybody's in a forest and there are zombies. Extremely complex for a Warcraft 3 map.
Tides of Blood. A pretty good AoS, not very popular and I don't remember it being very balanced either.
Ragos ORPG. Does horrible things with the English language but takes the popular ORPG formula and distills it. Ten levels, once you're at max it's all boss fights and cool stuff, also the only ORPG I know of with multiple maps. There are four or five different maps and they all use the same passwords so you can bring your guy from one to the other. That means the raid dungeons can be really complex.
Uther Party. Basically multiplayer Warioware, tons of fun.
World War Zombie. Basically a world war map but two players are zombies. Tends to be very one-sided. If France is quick he can fortify the catacombs and basically make it impossible for one of the zombie players to get started, and the second zombie player isn't as decisive a threat. If France can't get his shit together though the game's basically over as Europe will be overrun.
Lord of the Rings Risk. It's pretty fun, I don't remember much about it.
Star Trek. A twelve player Star Trek World War game, with several dozen planets to conquer and every major race as far as I know. There are four or five Independent Empires who usually end up being food for the other races. The Borg are pretty OP. The Romulan Warbird is extremely OP and most games ban it under the honor system. The rest of the races are pretty balance. Species 8472 starts out in fluid space and spends the first half hour or so unbelievably bored until they get a huge fleet, escape fluid space, and fuck everyone up, or someone makes a portal to fluid space before they're ready and ruins it.
Helms Deep. Basically the battle of Helms Deep. Lots of fun.
Fellowship of the Ring. Everybody gets to be a member of the fellowship and the game follows the entire story of Lord of the Rings. A really ambitious map and it's a lot of fun.