In Web applications [I've] seen numerous — and personally implemented a few — ways to rearrange items in a list. All of those were indirect interactions typically involving something like up/down arrows next to each item. The most heinous require server roundtrips for each modification...boo.
Then [I] came across Simon Cozens' example of rearranging a list via drag & drop. [I] was so inspired [I] had to try it out [myself].
Update 4/26: tested and working as expected in IE6, Firefox 1.0, and Safari 1.3, unless otherwise noted.