You may know that my company specializes in analysis software for investors and developers, but we also offer a pretty handy real estate calculator program with the following functions:

Monthly Payment
Maximum Loan
Amortization Schedule (for multiple loan types)
Six Functions of $1
Loan Spread
Mortgage Qualifier
Loan Comparison
Refinancing
Future Values
Income Multipliers
Depreciation
Underwriting
Discounted Cash Flows
Financial Ratios
Capitalization Rate
Bi-weekly Loan

Price is $19 at http://realdata.com/p/calculator/ You can get more info there as well. There is also a free version, with fewer functions.