Zvezda (The service module) has engines which can be used for boosting the orbit. Zvezda also has RCS, as does Zarya (The russian cargo module). I am not sure if any other current modules have RCS thrusters on them. I would assume that if there were more they would be on the ends of the truss system.
I believe that the planned SPP (the solar panels sticking up from the rest of it) was going to have thrusters which would provide roll capabilities.