Tim
This is exciting stuff and I have never seen a thread where the content is soliciting such constantly positive remarks from members of the forum. I really like the way you are listening to ideas and appreciate that it must be hard work to keep up with it like this.
For me it is timely as I have just bought a 5" touch screen colour GPS unit from Ebay for £46! for the purposes of testing out flight navigation software. I was interested in the Memory Map stand at the Sywell rally recently, but frankly couldn't get that many questions answered as there were other punters there all wanting information and only one salesman.
Without having seen your software running yet I can't comment much further, but when pilots realise that they don't have to pay silly money to get a fully functioning GPS flight planning and navigational unit and could possibly get a better unit for a fraction of the cost of those currently on the market, your project could be very successful when you go public.
When you eventually do, will you also be selling copies of "Sky Angel For Dummies"??