I'd love to hear about things that you "discovered" about a pin weeks or months after owning it.
For example, tonight while playing FH I noticed for the first time that the clock on the playfield counts down the end of modes line "hidden hallway multiball". It was a combination of "Wow, that's cool" and "Oh sh*t! How did I not notice that before?" I'm sure on the deeper games there are lot's of little things to notice.