Anything with the -i flag - that's how I started using perl (when sed/awk wasn't enough).
perl -MData::Dumper -MSome::Module -e "print Dumper [Some::Module->new()->mytest(@ARGV)]" parm1 parm2 etc to test either how some other module works, or to test how my new code is working - a little bit easier/faster than doing full tests when I'm still developing. Or I use it to show my subordinate how to use an API and what it produces when we're sharing a desktop via VNC.
Snippets of code should be wrapped in
<code> tags not<pre> tags. In fact, <pre>
tags should generally be avoided. If they must
be used, extreme care should be
taken to ensure that their contents do not
have long lines (<70 chars), in order to prevent
horizontal scrolling (and possible janitor
intervention).