There really isn't much use for a tool like this. I mostly made it just to have fun with python and mess around with pygments. One possible use case could be for generating images for a website perhaps? It might be neat to have a minimap of the code of a website as its background.
An editor or IDE could shell out to an arbitrary minimap generator instead of incorporating it inside. Composition of small components, each doing one thing well.
Free project idea: Upon reading the title, I imagined something that generates a minimap for the whole project, and files are laid out on the map according to how they relate to each other (the more tightly bound, the closer), so, for example, you could look at the "You are here" marker and see how far away from certain subsystems the current file is.
It's a condensed version of your code using color blocks instead of text.
The Sublime text editor used a similar view along the right side of the editor. You can use it to quickly navigate to a section of code without having to read each line.
In case anyone cares, this is an option in Visual Studio too. Under "Text Editor > All Languages > Scroll Bars", you have the option to "Use map mode for vertical scroll bar". Can also be configured on a per-language basis.
Finally I can make my callback pyramid of doom t-shirt, generated from an actual pyramid of doom.
Nice work.