James Edwards a.k.a. Brothercake‘s Docking boxes (dbx) is already included in WordPress; it powers the draggable boxes in the writing interface. With dbx, you can take semantic, structural markup and make it work well and look sharp prior to adding scripted behaviors, then use
id attributes and some external scripts to upgrade it into a beautiful and highly usable interface. What I find most impressive about this script is that the interface is 100% accessible via keyboard. If you don’t appreciate the full value of keyboard accessibility, go and break your wrists snowboarding and try to use your browser. If your insurance or your stomach won’t allow such drastic action, at least unplug your mouse until you appreciate it. The downside to dbx, and the only reason I couldn’t use it for this project, is that it doesn’t permit dragging items between different columnar lists.