Actually FlyerTalk/WebFlyer will be unveiling such a tool in the next few weeks. We completed a call with a source supplier just Monday and now are busy formatting the window for which the data will appear. That and we're trying to come up with a few clever names to call it so in the future most everyone will know what it is. The toll will concentrate on two levels of data - miles for EQMs, ie tell us how many miles you need and we'll sort out only those routes that will work along with the fare broken down by actual flight miles of the airline itself and a true mileage run tool that simply breaks down fares by cents per mile from particular cities.
anyway, hold on for a little while longer and you'll find something you can use that will be built-in to FlyerTalk, always much easier for us all.
As well the tool will be featured on WebFlyer and likely InsideFlyer as well.
Hope this helps.