What's a good way to make an open office more tolerable? My lab is a large rectangular room filled with desks and computers. I don't really have enough space to make cubicles, and I can't get more space. I'd love to improve the work space for my researchers.

Right now my lab is basically 3 rows of desks in an open office plan, with probably 6 people there on average, but closer to 10 during summers.