@jbooker
$().SPServices.SPLookupAddNew doesn't use modals because of this reason:
"While this function works with SharePoint 2010, because of the modal dialogs the user will get "lost". Alternatively, if you've turned off the modal dialogs, the function works just great."
I was referring to this thread with my post as well. I meant to post it here. :) I also meant that the problem stated in the docs with this function could probably be solved with my approach. Of course it'd have to work when modals aren't used or available, but I'm confident it's doable.
Cheers,
Matt