Once in a while there comes a web site, a tool - worthy of calling "pure genius."
Such is the case with HouseMath http://www.housemath.us/ created by retired (35 years old mind you) software developer Kirill Sheynkman. This site is pure genius, the author is pure genius.
Say someone is deciding between renting or purchasing, given appreciation, inflation, tax rates, tax benefits, capital gains, etc, etc... these assumptions can be done instantly.
While the site is limited to major US cities right now, it also appears that he has provided some development content tools (if someone is so inclinded).
HouseMath has to be the most revolutionary real estate financial sites to hit the web in as many years!!!

