I have determined just now that "oh, wouldn't it just be fantastic if I could somehow attach a hand-drawn diagram to a piece of code as a comment", and this would allow me to come back to something I worked on, days, weeks, months earlier and far more quickly re-grok my algorithms.
As a visual learner, I feel like this has the potential to improve my productivity with almost every type of programming because simple diagrams can help with understanding and reasoning about any type of non-trivial data structure. Graphs for example. During graph theory class at university I had only ever been able to truly comprehend the graph relationships that I could actually draw diagrammatical representations of.
No IDE to my knowledge lets you save a picture as a comment to code.
My thinking was that I or someone else could come up with some reasonably easy-to-use tool that can convert an image into a base64 binary string which I can then insert into my code.
If the conversion/insertion process can be streamlined enough it would allow a far better connection between the diagram and the actual code, so I no longer need to chronographically search through my notebooks. Even more awesome: plugins for the IDEs to automatically parse out and display the image. There is absolutely nothing difficult about this from a theoretical point of view.
What do people think? Would anyone pay for this? I would. But I would perhaps also point out that regardless of whether I or some significant number of my peers would pay for such a thing, the only way such a thing is likely to succeed would be through an open source release.