It took a few hours but I've gone and done it. I hacked out the "suggested tags" UI goodies from del.icio.us and grafted it into the Movable Type admin's "Edit Entry" template.
Now for my purposes, the "suggested tags" are a set of set slugs; terms another component of this behemoth of a project seeks out via a nice SQL LIKE statement and then republishes elsewhere. However, the core code allows me to use it to, say, feed in all my aggregated tags, suggested tags, popular tags, etc...
Movable Type's new "AltTemplatePath" config directive (3.16 up) makes hacking the UI much easier and less worrisome when upgrading time comes around.
And no, I didn't even open Hacking Movable Type yet. I swear.
