The most likely candidate I can think of is Winzig : http://muth.org/Robert/Winzig/

Actually I didn't think of it, I had forgotten all about it, although it had been ported to maemo 2005 at one time and I had tested it then (it worked :-). It just happened to be updated lately and came across my screen...

It is a python (pyGtk) app, featuring several simple PIM-like modules that can be used separately or inside a tabbed-notebook-like interface.

The author says most of the modules are based on a simple, flat-text database engine that can be used for various purposes.

I haven't looked in detail, but probably for someone familiar with python (which is easier to learn than most), using that engine and Winzig's examples on how to make CRUD forms would be the quickest way to get something working.