In a small space, folding furniture provides the ultimate flexibility, particularly for those of us that call our couch the office. For short sessions, a computer in the lap is fine, or some sort of pillow lap desk, but extended laptop on the couch use really calls for a dedicated table.
There are some good coffee table options out there that would give you a nice place to put your laptop while sitting on the couch, but if you would rather not replace your current table, this folding birch plywood tray is a nice space saving option. The hinged legs mean that the table just collapses straight down when it needs to be put away which also keeps the overall footprint small.
Available for $129 here.