Since I teach the Java programming language, I often need to draw UML class diagrams in my handouts. Of course, I prepare my handouts with LaTeX. Until yesterday, drawing class diagrams in LaTeX was a bit difficult for me. I used to use xfig for all my drawings (both in handouts, presentation and scientific articles), and I am moving to tikz for the new drawing I'm doing. But neither tikz nor xfig had the functionalities I need to easily draw class diagrams.
That was until I discovered pgf-umlcd. It provides a set of macros to ease this task. The problem is that there was only 2 commits in this project since its creations, last one back in Nov 2009, and the stuff didn't compile for me. So, I decided yesterday to fix it, even if I'm very far from being a TeX hacker. The result is that it's still a bit crude but it works for me.
EDIT: the project moved to github meanwhile.