Good stuff.
If anyone's looking for desktop applications ...
Notepad++ has most of these features.
Nimbletext is great when you need to do more complex stuff, e.g., transforming a list of field names into a Mongoose model.
Here's one that's on topic: Minimum price explorer -- helps you work out the absolute minimum you can charge for a software product.
And this one too the Should I automate it? calculator -- helps you work out if a thing is worth automating instead of doing manually.