I think the utility that you describe would be quite useful in quickly scanning IDF files. My suggestion would be to create a logical hierarchy of the objects according to Group -> Class -> Object -> Field and have a way to collapse or expand this hierarchy according to what you're looking for. The IDF editor sort of does this and the new Open Studio ModelEditor (
http://openstudio.nrel.gov/) is on the right track but not quite there yet.
I'd be happy to help with any feedback or beta testing of your utility - just email me: miller.clayton@xxxxxxxxx