This app did not make much sense to me because I was sitting at my computer making choices for myself and my non-present roommate. So the related article with useful visual explanation of Sperner's Lemma may be more useful reading if you don't have a quorum of your roommates to work with this morning:
Sperner's Lemma is cool, but since it can be gamed and your preferences will change anyway (so the envy-freeness is only temporary) it's more of a curiosity than a true solution.
http://www.nytimes.com/2014/04/29/science/to-divide-the-rent...