Ever seen tonicdev.io? Is it possible to use npm packages in notebooks?
If you save it as an HTML file you can obviously add your own client-side JS. Node packages are a ways off right now though - would need to think about how to do it as it's all client-side.
In addition, it might be cool to have in-line substitution of data. For example, in your analytics notebook[0], I noticed you referenced the number in text afterwards, but if Kajero was pulling from a live data source, it'd be neat to do something like this:
Predictably, most came from the US ({{data.analytics[0]}}). There were also a lot ({{data.analytics[1]}}) from the UK - this is probably mainly due to it being posted on my Facebook page, with these hits being from friends rather than internet randoms.