but text editing apps are a dime a dozen (prolly cheaper) and represents the "extreme generalization". there's gotta be something comparable.
let's say, for sake of discussing something tangable, your niche is landscaping. the landscaper arrives at a potential customer's home, initiates dialogue & offers the product, "while this consultation is free, we can provide you with a 3-d experience that will help you envision what we can do for $29.99 if you like?" while launching the app's demonstration of what it can do (eyecandy. mmmm!

). of course, the landscaper would already have a basic 3d model of the customer's home/propery based on google maps (or within the first 10 minutes of being on property?) to entice them.
the customer agrees and the 2 walk around the property and talk about design ideas. some trees & flowers here, rocks there, a winding pathway through it all. the landscaper, all the while, plotting the design through your app, quickly allowing the customer to "experience" what it would be like coming home to and living within the landscape.
tweak this, tweak that, add a gazebo (up-sell), and arrive at a couple/3 designs for the customer to choose. email them to the customer so they can invite their significant other to experience what they've come up with, with help from your app.
an app like that would be worth hundreds to a company. and, i'd offer additional licenses (above, the initial 1 that comes with the app) so the larger companies could utilize your app throroughly (while paying you what you deserve).
oh, and:
Quote: "Be sure to let us know what it is once it has been released! Good luck."
please.
Virtual Nomad @ California, USA . DBPro V7.7
AMD Phenomâ„¢ X4 9750 Quad-Core @ 2.4 GHz . 8 GB PC2-6400 RAM
ATI Radeon HD 3650 @ 512 MB . Vista Home Premium 64 Bit