The documentation wiki for Greasemonkey. Lots of greasy monkey goodness.
#javascript
Keyboard Events
Really thorough analysis of keyboard events and how they are handled via JavaScript in different browsers.
iui
iPhone UI library for developing web-based apps that look iPhone-ish.
FullCalendar
“FullCalendar is a jQuery plugin that provides a full-sized, drag & drop calendar like the one below. It uses AJAX to fetch events on-the-fly for each month and is easily configured to use your own feed format (an extension is provided for Google Calendar). It is visually customizable and exposes hooks for user-triggered events (like clicking or dragging an event).”
Hackvertor
Encode/decode every type of encoding known to man via JavaScript.
Appcelerator Titanium
“Titanium is the first open platform for building rich desktop applications.”
Quick Lookup
Nice AJAX-powered tool for quickly looking up PHP, MySQL, JS and CSS functions etc from their respective references.
Things you may not know about jQuery
Things you may not know about jQuery
Awesome list of tips for harnessing some of the hidden power of jQuery.
WireIt
A JavaScript wiring library for building a UI like Yahoo Pipes.