awesome (all lower case) is another tiling window manager. But, boy howdy, is it a good one. It’s highly configurable and extensible using the Lua scripting language. No mouse is required, and it provides great support for multiple monitors. And, of course, it's fast as lightning, which brings us to the end of this list. Keeping this down to just 10 was certainly a challenge. Did I miss your favorite, ultra-cool (but under-utilized) Linux/Unix Desktop Environment? Toss a note in the comments here or let me know over on G+.