I've been a long-time Vim user. To the extent that I have a customized calendar syntax and keybindings written for it, I often do filesystem management operations (rename a bunch of oddly-named files to unified format), and so forth within the editor.
People accuse emacs of being the kitchen sink, but you can do pretty much the same stuff within Vim, it just starts up faster, has a different set of keybindings, and has that whole "Mode" thing going on.
Regardless, I've started using folds in Vim, and it's a really really useful feature. I've known about it for a long time, but never really saw the point. Now I do... it allows you to get rid of all the irrelevant context and focus on the meat of whatever you're doing. Makes paper writing much easier; you can fold each section and see the outline, or collapse everything except for the section you're working on and the abstract. Handy.