Homeowners rushed to take advantage of last week's drop in interest rates after the government's takeover of Fannie Mae and Freddie Mac, but rates are rising again on investor fears about the eroding conditions in financial markets. Many online lenders offer competitive packages for home buyers and most of these offer free online mortgage quotes for your perusal. As a perk, some of these sites also offer free online mortgage calculators to help you calculate the costs and gains of the loan programs they have to offer.