Custom Post Permalinks will set up custom post type permalinks for non-hierarchical permalinks which have the flexibility of blog post permalinks.
Dev Corner Badge places a highly visible marker in the upper corner of every post/page to denote a development site.
Favicon Rotator is a free plugin for WordPress that makes it incredibly simple to add a favicon to your site. Favicon Rotator uses WordPress’ own media management features to upload and add a favicon to your site so there is nothing new to learn.
Trigger Warning allows you to wrap content in quicktags to hide it. Readers can choose to read the trigger content by clicking on the “Show” button.
WP Tweet Button implements Twitter’s own Tweet Button on your blog or site. The tweet button can be positioned as you please and can be styled to your delight in the settings page.
Fast Secure Contact Form lets your visitors send you a quick E-mail message and blocks all common spammer tactics.
Simple Twitter Connect is a series of plugins that lets you add any sort of Twitter functionality you like to a WordPress blog.
Twitter Goodies will show your twitter tweets under Sidebar Area (Widget) and Post and/or Pages.
Twitter Tools integrates your WordPress blog with your Twitter account allowing you to send new blog posts to Twitter as a tweet and vice versa.
WPBook enables you to pull recent blog posts from your blog in to Facebook, and allow Facebook users to enter comments. Their comments show up on your blog whether accessed directly or through Facebook, and regular blog comments will show up in Facebook as well.