I do Recursively Palindrome in 26 keystrokes using keyboard macros and recursive editing.
I do VimGolf formatted text to markdown in Emacs and trip the life fantastic.
It's big! It's gold! It's fancy! I like it!
I'd demonstrate how to use elisp in a query-replace-regexp command to align a column of numbers based on the position of the '.'.
I do the VimGolf Line Zipper challenge in Emacs in about 16 keystrokes. I cover isearch features, window configuration registers, and keyboard macros.
Just a place to drop my Emacs videos.
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I think you can do #5 faster with elisp in regexp-replace. Here's a nice article by Steve Yegge on it: (steve-yegge.blogspot.com/2006/06/shiny-and-new-emacs-22.html)