Well, I used to work at the college I attended... and I could wear whatever I wanted. Most of the time I was hacking away right next to the PBX in a back corner of a basement, so it didn't matter anyway (probably only a dozen or two people even know that room exists). Now that I actually have a professional career, there is a formal dress code (pants of some sort and a shirt with a collar), but our R&D division is thousands of miles from management, so here, anything decent goes, as long as you're not meeting with anybody. I usually wear a polo shirt and jeans (the air conditioning is pretty cold). Others wear really ratty T-shirts, cargo shorts, and sandals. Technical management usually dresses up more, but you'll almost never see ties here.