Innovative keyword checker

Ok, I'm looking for a program that will run as a piece of stand alone software and as a web based application. I need it to look up a URL (input on site or on applic) and then find out any keywords that site is ranked for. This is important, it should not look at Meta Tags. Websites are often indexed for keywords that are not listed in the meta tags and so far the web only really offers an application that means you have to enter a URL and keywords to check ranking. I want an application that will find out every keyword a site is indexed for and then give the rankings with each of the major search engines. For the web based applic there should be the capacity to offer a trial version that gives results for 5 of the keywords, or only gives the results from a select number of search engines giving me the capability to demo it and sell the full product. There is no website for this as yet, that will need to be designed in the future. I am willing to consider a profit share or virtually any method of payment. Yes, that's right, even cold hard currency (unmarked, used $20 bills) in a brown paper bag in the superstore car park. Please PM me with details and any problems you believe there may be. I know that this can be done, I simply don't know how to do it.