A little flowchart describing how, given plugin X, you could determine if it was conflicting with some other plugin Y, or with your theme. This is a nice helper from Scribu.
Remi Corson has a landing page up for WPBillings, a free CRM tool for WordPress he's building. Looks very interesting. You can go to the site to sign up for when they launch. Looks like another great "WordPress as an…