Although your question is specifically about the USA, I thought an insight into a typical European setup would be interesting as well. I imagine it will be very similar to what you find in many American centers.
The image is from Copenhagen Area Control Centre (Denmark) and shows a normal controller working position. You will notice five screens in total.
The largest screen, immediately in front of the controller, is the main situational display. It is essentially the radar screen, showing different aircraft in their geographical position in relation to airspaces and other traffic. Typically, the situational display will also, depending on the specific system, enable the controller to interact with aircraft labels, for instance to enter notes about clearances and instructions and show them directly on the display.
To the left is a secondary screen which also shows information about traffic in the area. Here, the traffic is presented in text lists, which allows the controller to get a thorough overview of what is currently going on, and what is coming. This is basically a replacement for old fashioned paper flight strips (which are being phased out across the world). In this example, it also features the arrival management (AMAN) system.
Below the main situational display there are three screens. From left to right, the first one is a telephone panel, which gives the controller easy access to all relevant phone communication lines. It is a touch screen, and by pressing any button on the screen, the controller can call adjacent ATC sectors, control towers, emergency services, the meteorological office etc. to coordinate.
The lower middle screen can show a lot of different information. On the image above, it is set up to show the frequencies of other ATC sectors in the area along with any active military areas. It can also be used to retrieve meteorological information or anything else that might be relevant.
Finally, in the lower right corner is the voice communication system (VCS) interface. Also a touch screen, here you have control buttons for the VHF radio equipment, used to communicate with aircraft. The controller will be able to toggle which radio frequencies are used to transmit and receive, and will receive information about any radio equipment that might not be working as it should.
Apart from the actual computer screens, you will notice the backup phone to the left and a clock above it. There is also a backup VHF radio in the upper right of the console, but that cannot be seen on the above image.