My nephew and I like to play games together, and we're always looking for games that we can play together. I was manually looking through my Steam library today and wondering how to go about finding stuff that we may already own that we could play together. Is there a tool for that? Or maybe something that could suggest a game for purchase that we would both enjoy based on our history?

Also feel free to drop any general game library organization tips here. I found this tildes thread from a couple of years ago and I've already seen some cool ideas and tools.

I'm currently reorganizing my Steam library, as I do every other year or so, and I'm curious as to how people here organize things (or not). Do you have certain categories or a taxonomy you put your games into? What are the benefits and limitations for the way you've chosen?