Shelving, whether wall-mounted or freestanding, creates a dramatic backdrop behind the sofa. In the middle of a room, you can use open shelving to divide a space and anchor your couch. (This photo is from our old apartment. We've since given away the shelves, but this arrangement served us well for a long time.)
This sweet steup is from Design Sponge's Sneak Peak of Tonya and Mike Sutfin. They created a breakfast nook behind their couch using a folding table and a couple of chairs.
This sofa setup comes from an AT post on 5 Alternative Uses for a Desk. Any sofa table can be converted into a desk by adding a chair and a task lamp.
In Jessica and Alex's home, the space behind the sofa provides room for storage. The credenza also defines the space between their interior columns, creating a sense of balance.
Lastly, if your sofa is built for viewing from any angle, how about keeping the area behind it clear and showing off its sexy backside? This is the Polder Sofa from Vitra.