Alex King has created a number of good Wordpress plugins , including a WordPress Mobile Edition plugin that automatically generates a PDA friendly version of your blog.

Popularity Contest

This plugin will help you see which of your posts are most popular. Views, comments, etc. are tracked and given point values to determine popularity. Latest Release: Version 1.1, 2005-07-28. The latest version (including unreleased bug fixes) can always be found here.

WordPress Mobile Edition

A PDA friendly interface for your blog. It’s (almost) XHTML compliant. You can see it in action on my site. Latest Release: Version 1.8, 2006-03-02.

WP Since Last Visit

Shows the number of new posts and comments (including indicators showing what posts and comments are new) since a visitor last came to your blog. You can see it in action on my site. Latest Release: Version 2.2, 2004-07-05.

WP Unformatted

This allows you to add custom fields to a post to disable auto-formatting and/or auto-smart-quote conversion. Latest Release: Version 1.0, 2004-05-21.

WP Grins

This plugin allows you to put clickable smilies on your post and comments forms. Can’t remember the right syntax for one of the smilies? Just click on it and it will be inserted right into your post/comment. Latest release: Version 1.1, 2004-05-12.