Here is an example interactive form application. The interface UI is driven by the built-in webserver. It's based on some of the code in Ole's file transfer script. However, in this case, the pages are served directly to the web browser component inside Pythonista. You do not need to view it from another computer--although, if you know the device's address you can do that too.
I am a newbie to Python and GitHub, so my apologies if there are style or formatting errors. I have tested this on my iPhone and two iPads (it was written on a mini) as well as a desktop and laptop.
I think using an HTML forms interface is a good way to produce easy to use, interactive applications. I hope this example will demonstrate some of the possibilities. Let me know what you think.
Note: the gist above is now outdated. I have made a number of improvements since this initial post. Please use the newer gist shown in my second post, below.