ND1 v1.6 will allow users to create applets / calculation tools inside the app and share them. There will be upload/download functions and an interface for tool sharing just like the one for sharing of folders (in My Data).
You'll be able to switch between calculators/applets/calculation tools by tapping one in a new "Calculators" list.
And you'll be able to edit them. You've always been able to create your own keys and calculator key layouts. Starting with v1.6, you'll be able to save them and share them.
For building a tool, a whole new set of UI (User Interface) components will become at your disposal: sliders, text fields, labels, 2- and 3-dimensional pickers, a date picker, segmented controls, a slider button.
You'll be able to build all kinds of tools. No coding required.
The upcoming CAS gives you access to calling Wolfram Alpha directly with your own queries. It allows you to harness W|A and Mathematica for results that can be used in subsequent computations. Given the awesomeness and power of those two tools, the sky's the limit.
Sliders and touch control allow you to build things like interactive graphers with text fields for formula input. (The existing method of needing a graphing equation in an 'EQ' variable is admittedly pretty lame.) Or leverage ND1's FFT function and the HTML5 canvas display to build your own spectral analyzer.
Advanced tools require some coding (via each tools injection page), but many tools can be built without it, thanks to a mechanism that defines UI elements with buttons. (All via pushes onto the stack.)
This UI-building mechanism will supersede UIs built with traditional coding. (Now you know why ND1 lacked those abilities.) From your own functions, you'll be able to invoke UIs. Eventually, not in the first release, you'll be able to build multi-screen applets.
To give you a taste of what's to come, here're a few posts introducing example tools, with info on how they were built.
New Calculators page:
New Calculators download page: