Not really a solution for a large, existing app, but ...
at a previous work place, we had a class header for each object. Like an event/function header, but added to the Instance Variables section of an object with the object name and brief description. Therefore each object had it's own name as a string inside of it, which would show up in a search.
I found this incredibly useful, and not only for searching for object references. Would definitely recommend this approach for a new application.
That probably won't help in your situation though, for that I agree with the other suggestions about using the object browser as a good way to find an object.