Direct X 11 + Unity
Got a new graphics card a couple weeks ago and wanted to put it through its paces. I was pleased with my purchase, and with all the cool Direct X 11 features exposed in Unity 4
Got a beta version of Unity 4 to play with and (not) coincidentally picked up an Nvidia 660 Ti. Just spent a couple hours getting comfortable with the awesome physics, deferred rendering, soft bodies, point light shadows, SSAO, DOF, Bokeh, Chromatic Aberration, and some other stuff. It is REALLY fun to play around with!