dp.SyntaxHighlighter – free JavaScript syntax highlighting: This is an insanely well-done syntax-hilighter in JavaScript. Just dump code in a CSSed textarea, and it comes out looking like these examples, which are nuts.
The script is meant to help a developer to post code snippets online with ease and without having to worry about applying format. People who use blogs like MovableType, .Text (dotText), dasBlog and any other system can easily add code to their posts.