Consider a case when I want to try some idea of an application. But I want to avoid investing a lot of effort in coding UI/work flows/database schema etc before I see that it's going to be useful to me (as example of potential user). My idea is stay lightweight and put all the data in text files. So the components could be following:

1. Domain objects are represented by text files or their fragments
2. Domain objects are grouped by their type using directories
3. Structure the files using some both human- and machine-friendly format, e.g. YAML
4. Use some smart text editor (e.g. vim, emacs, rubymine) to edit and navigate those files
5. Use color schemes and macros/custom commands of the text editor to effectively manipulate those files
6. Use scripts (or a lightweight web framework like Sinatra) to try some business logic ideas on top of the data model

The question is: Are there tools or toolkits that support or can be adopted to this approach? Also any ideas, links to articles/other knowledge sources are very welcome.

And more specific question: What is the simplest way to index and update index of files with YAML files?