I went ahead and put this up, too:
http://www.independentdeveloper.com/...eparent-object
Its a plugin that gives you a pop-up dialog where you can type in the names of an object or group to change its parent. I wrote this ages ago as the older versions of AC3D didn't let you drag and drop in the Hierarchy view (either that, or I never figured out how, lol
).
I still use it occassionally, so it's been updated for the current version of AC3D.