Some things I've written:
- Placeholders.js - An HTML5 placeholder attribute polyfill. No dependencies on jQuery.
- jslinterrors.com - Get detailed explanations of JSLint error messages.
- Patterns.js - An HTML5 pattern attribute polyfill. No dependencies, and works in IE6!
- Progressive.js - Interact with the DOM before it's ready!
- gzipper - Find the gzipped size of any file or text
- Notepad++ jQuery code hints - A Notepad++ plugin to provide jQuery autocompletion.