Weezer Dam comprises the Dam itself, a pathway from the Open Prairie to Adamant Canyon, and the small Weezer Village. The village can be reached via the Dam or by heading immediately north once you enter Adamant Canyon. Both the path and the village are freezing cold during both day and night, it is therefore advisable to purchase a Parka or other warm clothes from a player or Austen's Furriers in the village if you plan on wandering around. You can move around Weezer bare-ass naked if you duck from building to building and run exceptionally fast (or swim in the water, it's warm) but for the price of some wooly underpants, why risk it?
Weezer Village has a number of stores selling otherwise hard-to-obtain goods, these include Austen's Furriers (Warm clothing), Hendresson's Prion (Helicopters!) and Carhart Laboratory Supply (Puppies! No, seriously, it's what it sounds like.) There's also the slightly more mundane Mercy Shoppes (medical supplies) and A Better Life (implants).
Other locations of note are the Dojo (dodge and fists training) and the Semenarium, where Jack will pay you a one-time fee to jizz in a bottle and hand it over to him without asking too many pesky questions. For a full list of stores, please see the shopping list.
Weezer Dam has its own (rather small) sewer system, with a few luckless clones wandering around. They're not too tough, but if you're prone to taking beat damage it'd be wise to steer clear of them.
There is a Helipad on the northern side of the village, along a pathway carved from the ice. Be fast if you don't have decent clothing or you'll freeze to death, and know that you can jump in the hot spring river to warm yourself up. It costs a little over $1000 to fly from Weezer to Any Port, and vice versa.
A detailed map with descriptions can be found here.