I always bind super-left and super-right to https://gist.github.com/unhammer/5336830 (requires wmctrl and xorg-xdpyinfo), so I can tile any two windows left/right. Also handy when e.g. reading an article while note-taking, watching a screencast while chatting, etc.

I guess I should try a tiling window manager some day, but I almost never need more than fullscreen vs 50/50.