Buying a home is very interesting. It makes one question own priorities, look into expeses, and consolidate savings. A lot of choices must be narrowed down (buy expensive or commute longer, small sunny or large dark apartment, 7ARM, 15 yr fixed or 30 yr fixed loan...)
I made an OpenOffice spreadsheet to help me narrow the mortgage choices. This involved deriving the payment function, and coding it in StarOffice BASIC. I did a similar thing in Excel a couple of years ago, but could not find the file. Ah ... all the information should be stored on the web!
I found all online calculators to be deficient, because they are mostly written for bankers and not with the customer's interest (pun) in mind. This spreadsheet answers the question 'which loan is the best?', given the price of the property and amount of the buyer's savings. All other calculators list points and closing costs as separate items not included in the total amount of cash available at hand. The best on-line thingie I found was Karl's Mortgage Calculator.