Feature request: custom widgets

Metabase is really great product with many useful options and great UX.
Many people have different needs that are not always main stream, and will likely never make it into the product.
That is why I think that enabling customization is important. It allows people to adjust and tweak the product to meet their needs without waiting for features that will never get it into the system.

I can think of different ways to extend Metabase, but specifically I’m interested in creating custom widgets.
This could be in the form of a simple HTML widget (let’s say using some template engine), or a full blown plugin system.

For example, I would like to present the status of some of our systems using shields.io badges.
I’m pulling data from mysql db in order to create an svg of the form:

In an HTML custom widget it could look like (pseudocode, choose whatever template flavor you like):

{{for status in states}}
{{end for}}