WordPress Configuration Tricks : If you have ever installed WordPress and wanted to know what else you could do with your wp-config.php file, this is the blog post to read. As Ozh points out in the comments, a couple of tricks were left out but nothing that could not be remedied with a simple Google search (e.g. WP_HTTP) as long as you know what you are looking for.
Tips from that page that got me thinking (things that make you go hmmmmm?) include moving your wp-content directory, increasing your memory limit, changing the autosave interval, turning on debugging and finally the ability to specify a log file for errors. All of this through the wondrous wp-config.php file. The list is quite exhaustive.
While you are there, make sure you subscribe to the blog. Chris and Jeff are putting out some good stuff!