A wee while about (well, more than two years ago) I wrote a little Matlab programm called arrowh.m, which draws cute little arrowheads to your plots (particularily usefull for phase plane plots, nyquist plots, etc.).
A few weeks back, Oskar Vivero asked me if it was ok to include that little function in his toolbox. Of course it is, I’m very honoured by the fact, that one of my little programs gets to go into a fullblown toolbox!! So make sure you have a look at the MIMO Toolbox, it looks very useful and well done.
I’ve also written a number of tips & tricks into the forum of my course of study, you may want to check that out too.