Author: Anonymous Unix Wizard

 stac
======

 $ sed -nE '1{h;b;};$!{G;x;};${G;p;}' file.txt

 Explanation: simple tac (print a file from the last line upwards)

 Acronybanner
==============

 $ banner `echo "My Personal Acronybanner " | sed -E 's/([1-9a-zA-z])[-a-zA-Z]+ /\1/g'`

 Explanation: Make a banner acronym from a string given as input. 
 Comment: Slightly modified to create the logo of the U1FFF. Put a space
          after the last word ;)

 snl
=====
 
 $ cat file.txt | sed "=" | sed -n "N;s/\n/       /;p;d;"

 Explanation: number lines in a file when you don't have nl(1)
 Comment: the stuff after "\n/" is actually a TAB.