On the CatsWhoCode.com blog there's their list of top "hacks" for WordPress that can add that little extra boost your site might be needing.

2009 has been a very prolific year for WordPress hacks. In this article, I’ll show you the most useful hacks I came across during the whole year. Enjoy!

Some of the suggestions include:

• Monetizing your old blog posts
• Detect the visitor browser within WordPress
• Get short urls for social bookmarking
• Use SSL on wp-admin directory
• Post on your WordPress blog using PHP