Let’s you use correct syntax on your code snippets, or rather – keeps WordPress from fucking up your code.
Download from here. To use, wrap your code with
<pre lang="LANGUAGE" line="1">and
line=”1″ is optional. This is based on syntax highlighting from GeSHI. You can visit their page for a full list of supported languages. The ones I care about are – or rather, may care about in the future: