Two minor things:
A simple shell-script to submit metrics to a graphite server, extensible via local plugins, but covers the obvious metrics by default.
Metrics are submitted via simple calls to netcat.
Trivial, but much more lightweight than collectd and similar.
A perl module for converting HTML like "<p>:smile:</p>" into something graphical.
This was written for my markdown sharing site, but is pretty fun.
The konami-code page demonstrates usage.
(This parses the HTML so it won't transform attributes, ids, or anything that isn't in the "text" part of any HTML input.)
The graphite sending script is perhaps the most useful, but at the same time it feels too small to be a package of its own. I'm tempted to bundle it up into my sysadmin-util collection, but I can't quite decide if it belongs there either.