http://www.perlmonks.org?node_id=60611

Takes in an HTML page and extracts everything that looks like a ZIP code (that is, 5 digits in a row.) Prints them out, separated by commas. I'm sure there's an better way to do this, but thought I'd share. :)
cat zips.html | perl -ne 's/(\d{5,})//g; print "$1," if $1'