After trying out a few code snippet plugins for WordPress, and not having much luck, I found CodeColorer. CodeColorer creates a nice code box for your snippet, which is quite visually appealing. Here’s an example of some php:
Once you look at the code snippet that CodeColorer outputs, though, you start to get a sense of everything that it can actually do. For example, mouse over one of the functions above, and you’ll notice it links you to the appropriate function reference on php.net. I’ve just started working with the plugin, so I’m sure I haven’t tapped all the features yet, but so far I’m quite impressed.