Thanks to Martin Krafft for the inspiration.
fi
# press "ctrl-e d" to insert the actual date in the form yyyy-mm-dd
-_bkdate() { BUFFER="$BUFFER$(date '+%F')"; CURSOR=$#BUFFER; }
-zle -N _bkdate
+insert-datestamp() { LBUFFER+=${(%):-'%D{%Y-%m-%d}'}; }
+zle -N insert-datestamp
#k# Insert a timestamp on the command line (yyyy-mm-dd)
-bindkey '^Ed' _bkdate
+bindkey '^Ed' insert-datestamp
# press esc-m for inserting last typed word again (thanks to caphuso!)
insert-last-typed-word() { zle insert-last-word -- 0 -1 };