This plugin lets you show a different greeting message to your new visitors depending on their referrer url. For example, when a Digg user clicks through from Digg, they will see a message reminding them to digg your post if they like it.

A store locator / location finder plugin that gives Web developers & non-developers alike the power to
create sites in Wordpress which showcase important stores or other important locations in a easily searchable manner.

Most interesting "twitter pack" out there...

"In this context, there is the question of why Core Plugins, why not the classic models of the Plugins in the wordpress.org Plugin Repository? This directory shows particularly how active and strong the WordPress community is, but the variety of Plugins is immense and an examination of the code is for the individual Plugins not guaranteed (which I in fact also support, as long as they are GPL, but that's another discussion). I see the possibility of the Core Plugins differently, because they could give such security and the same standard as the core itself."

"A set of macros that are intended to create a photo album in Impress from a set of graphics files in a directory. The presentation can then be edited, exported to another format, etc. "

Super extra useful for quick reviews and annotations of designs/wireframes etc.

A Helper is a plugin to incorporate the WYM editor into your Rails views. WYMeditor is a web-based WYSIWYM XHTML editor. Not a visual layout editor - structure and meaning only - trying to give the user an experience similiar to WYSIWYG.

The WordPress Automatic Upgrade Plugin, created by Keith Dsouza of Techie Buzz, is one of the best WordPress plugins ever written. It makes upgrading WordPress quick and super easy, letting you know exactly it what is doing each step of the way.