Years ago I hacked together the "Multi-Machine Parts Search", at http://moll.no/pinball/parts/. Knowing how that sausage was made, it is somewhat incredible that a) it's still alive, and b) people still find it useful. Considering that last fact, I don't want to mess with it too much, as its simplicity is one of its (few) strengths.
But, one thing I have long wanted to do is to somehow provide some search functionality without losing the structural information contained in the original parts list. So, I did some quick hackery today. If you go to the page and click the small tree icon next to a machine's name, you'll get to a searchable tree-view of the parts structure. Not sure how useful it actually is, but it's something. I have a few ideas for improvements already, but I'll still try to keep it simple.