I was thinking about Conway's audioactive sequence and how easy it would be to write a perl program generating it. Well, here it is, as a oneliner:
(this waits for user to press return before emitting the next term of the sequence.)perl -e '$_=1;print,s/((\d)\2*)/(length$1).$2/ge while~<>'
By comparison see e.g. this link. (Please note however that it's just a random hit from Google: don't consider it to have an absolute indicative power.)