Cool calculator, lots of fun to play with, looking forward to updates.
To cover your ass, I would put a big disclaimer at the bottom of every page that went something like this "Please see Assumptions. While every effort has been made to ensure the accuracy of this calculator, this website and its creator(s) can not be held liable for any damages or losses, monetary or other, from the use of this calculator or information provided on this website. Please use this calculator at your own risk and consult a professional for financial advice."