[EMACS]smex-mode

function: show most recently executed commands

useful key strokes: 
C-s/C-r switches to the next/previous match. 
Enter executes the selected command. 
C-h f runs describe-function on the currently selected command. 
M-.jumps to the definition of the selected command. 
C-h w shows the key bindings for the selected command. 
smex-show-unbound-commands shows frequently used commands that have no key bindings. 
smex-major-mode-commands limited to commands that are relevant to the active major mode.

https://github.com/nonsequitur/smex