There are some free-to-play games in my list that I've never (that I recall) played (AdVenture Capitalist, Double Action: Boogaloo). I think hey shouldn't show up in my list until I play them. Team Fortress 2, on the other hand, I have played, so it should be in the list, but it isn't. :-)

In general, I could see being able to exclude games from the list could be useful, too.