I did a google search for an iSight eye tracking program last week and found iTracker. A sweet little program for the Mac (and PC) that is cheap ($30 for the Mac version) and runs quite well! It is lacking in a few functions, but according to the developer, they are adding them in the next release, but for basic head mouse users, or to just add to your tool box of things to have on hand it is quite functional and worthwhile to have on hand!
Here is some video of me using it with Speaking Dynamically Pro on an iMac. Sorry for the poor quality!
More video of it in use with student soon.
"High-end" technology for the masses! Hurray!