Road Redemption in particular I am really looking forward to as I used to love the classic Road Rash games back in the '90s. They should be releasing alpha builds to kickstarter supporters who paid $40 or more in the next month or so, can't wait to give it a try. They are still actually taking donations via paypal on their site and putting those funds towards the stretch goals and you still get the kickstarter related tier gifts as well.
There are already some decent adventure games available via Steam for Linux: The Book of Unwritten Tales and it's sequel, The Leisure Suit Larry remake, and The Raven which was recently released to name a few. Haven't really seen anything as far as flying games though.