Been working on my 3d and 2d game engines, C# based shading language and relevant tools for the past 4 months.
I had rendering working nicely but then I decided to switch to a multithreaded gameloop and the AZDO model so I'm still getting the ubershader generator and texture arrays set up.
Also been working on designs for my survival horror game with some quick renderings (in blender)
http://i.imgur.com/QL0Xw4q.jpg
I'd love to get results like that in my game engine but that's still far off.
I've also been thinking about sphere-trees for compute shader physics and from the same data, distance-field global illumination, but I'm not sure if that will be feasible.
Other than that I'm doing on and off research on game AI and procedural art and music.
Actually I've been working on the game engines for almost 2 years but I didn't get satisfied with my engine design until a few months ago (as a result I made a lot of rewrites).
Oh and when I'm not doing any of the above, I'm watching anime!