Most people know that the at-command is used for replaying macros. However, most don't realize that this is just a normal register, and that you can copy/paste and even edit these macros.
Very very friggin useful.
(note: below, wherever ^M is mentioned, enter it using: ctrl-V, ctrl-M.
Things I commonly use the at-command for:
:!% 2>&1|less -i^M :!% 2>/dev/null|less -i^M :!%|grep -i only-show-lines-with-these|less -1^MWhen a script outputs ANSI colors, this is useful:
:!% 2>&1|less -i -raw^M