Here are a few really nice features I've picked up on recently that should be adopted by others:
Dishonored has a little check box with your progress details that shows if you are still on track for the no kills achievement. No more playing through an entire game and only finding out you screwed up somewhere when the achievement doesn't pop.
In Far Cry 3 and Dragons Dogma you can slide down sloping cliffs. It isn't fool proof. Try it in the wrong place and you'll die but it's an excellent way to let you make swift progress down from high areas.
Max Payne 3 gives you xp in multiplayer while playing singleplayer. A very civilised approach. If I don't care about the campaign I can play multiplayer and progress that way but if I want to play through the singleplayer once or twice I won't be starting from a cold zero when I finally get to multiplayer.