I have actually recently been working on something vaguely similar to this (well, the opposite of this, I guess) - a mileage earning calculator, but specific to Diamond Club. You enter your route, fare buckets and airlines, as well as Diamond Club status level, and it should give you an accurate printout of status and destination miles earned. It's not finished yet, but if I get some time to finish it up, I could conceivably then help you convert this useful spreadsheet into a web application.