Terry Fagan's excellent freeware medical calculator, ICUmath, has been updated with new calculators and improved accuracy.
ICUmath features 85 equations for adult intensive care medicine, including pulmonary, cardiology, BNP CHF nomogram, pharmacokinetic dosing, renal, electrolyte, chemistry, nutrition, TPN, perioperative risk, biostatistics, ACLS, Apache II, unit conversions, rules of thumb, and an RPN calculator with TVM.