Thanks so much for starting this thread, Helen! I love pens. My current favorites are the Pilot V-5 Extra Fine Point roller ball pens, which come in lots of colors. They're great for taking notes in class because they write smoothly and the ink dries super-fast.
I would like to get a fountain pen from Levenger (hi Alex) eventually, but I'm not sure it will fit into my student's budget at the moment.