I have seen people running a tiled window manager (like dwm, awesome, Xmonad) handling a tabbed terminal running a terminal multiplexer (like tmux, screen) running a text editor that supports split panes.
3 layers of window management leads to a lot of flexibility, and possibly complexity (especially when trying to remember which layer you're at so you know what key-binding to use).
If you use 2 or more of these window management layers, how do you manage your windows? Which features do you use and which features don't you use? Please indicate your platform.