The data I'm having the user order is not only order-specific, but is recursive. That is, one of the items on the list, rather than be a letter like "B" can be a list in and of itself. It's basically like "files and folders"
A major problem isn't only the UI, which took me days to make (drag and drop for files/folders ... anybody seen anything like this done before in HTML+JS?), but mostly is in the updating/validation. I receive information, like "moved item: /path/to/item to before /some/other/path" and I now need to make sure this is a valid action (eg: can't put a folder into one of its own subfolders, can't put a file in a file, etc), and also update the database to reflect this.
I chose to use JSON to encode objects in the DB, then decode them into an array, and do some easy/fast array stuff to perform the action they requested. Just judging on the array code, which does several "isset()" calls and splices, I'd imagine doing this with a DB would be a major heartache... but I have no doubt you'd be able to come up with some brilliant way to do it.
To each their own :)