I think some people prefer commenting over deleting on version-control - that way, they can see how this code used to look like in the past.<p>It would be nice to have an emacs or vim plugin in which you select a block of code, and it slowly walks back the graph of commits, showing each commit for 5 seconds. That way you could nicely see how your code-block evolved over time... (of course in many cases the code-block itself is useless without context)