Direct manipulation, particularly drag and drop, is under utilized in desktop applications and is almost non-existant in web applications. That's in the process of changing.
A collection of Direct Manipulation examples that work in modern browsers. Each example is a proof of concept. I'm answering the technical question "Can I do this?" as opposed to the interaction design question "Should I do this?".
Most of the JavaScript has been bundled into a reusable package called the ToolMan DHTML Library which you can download and use for free.
The dragging script was originally based on Youngpup's DOM-Drag. Sorting was originally based on Simon Cozen's Javascript drag-and-drop ordered lists.
Quirksmode has been invaluable across the board.