WordPress plugin that allows you to edit posts “in-line” in your normal blog pages, rather than requiring you to go to the Admin Panel.
#plugin
WordPress OpenID plugin
WPMU has one built in, but this is a consumer-facing one?
WP Plugin: Genki Announcement » Ericulous
WP Plugin: Genki Announcement » Ericulous
This might be handy at least as the foundation for an announcement/tips system.
Google (XML) Sitemaps Generator for WordPress
Google (XML) Sitemaps Generator for WordPress
Plugin to automatically generate a search engine friendly sitemap of your blog if it’s based on WP.
Amazon S3 plugin for WordPress
Amazon S3 plugin for WordPress
A plugin that makes your uploads through WordPress store on S3.
Urban Giraffe WordPress Plugins
Urban Giraffe WordPress Plugins
Some good plugins for WordPress.
Cimy User Extra Fields for WordPress
Cimy User Extra Fields for WordPress
A plugin which is apparently somewhat wpmu compatible that allows additional fields to be added to profiles.
Weblog Tools Collection » Blog Archive » Localizing a WordPress Plugin Using poEdit
Weblog Tools Collection » Blog Archive » Localizing a WordPress Plugin Using poEdit
Good tutorial on localizing the language used in plugins and themes via Gettext.
Writing a Plugin « WordPress Codex
Writing a Plugin « WordPress Codex
The official document on how to write a plugin for WordPress (single user).
How to Write Plugins for WordPress MU at IT Damager
How to Write Plugins for WordPress MU at IT Damager
Plugins for WordPress and WordPress MU are very similar but there are a few specific MU commands and plugin placement differences you should consider when creating a plugin for WPMU.