I think the following idea will be beneficial to all programers. You can contribute bitcoin to the bounty, if you like the idea.
The idea is to be able to see a history of changes to a piece of code. This is the next logical step to git blame, only you see many blames in history. Also, you can restrict the view to a certain range of lines, otherwise, it is impossible to follow visually. For example, you can restrict the view to a function, and see how it evolved. Or you can start with a patch, and see how every line in the patch came to be historically. At every view, you can see the commit comment. The presenation can be done as a slideshow-like player, with Next, Previous buttons. This would also be good for demo'ing some basic programs -- looking how each change builds up the demo.
Money collected in this pot will go to the first person or company who will implement such a tool, provided that the platform is a mainstream one: diff, git, Jira, etc. -- so that many people will see it in action, and implement on their end as well, as a reaction.
To contribute to the bounty:
https://booster.io/tipjar/0cbgxwl