Excerpts from Gwern Branwen's message of Wed Apr 08 11:43:46 -0600 2009:
One idea I've always wondered about is a menubar based tiling WM. The user, say, middle-clicks (hardly anyone uses middle-click), and then a geometrical menu pops up along the lines of XMonad.Actions.GridSelect. In it are all the default operations - 'kill', 'refresh', 'sendMessage NextLayout', etc. The user left-clicks on one and voila.
Further refinements: the menu could be shaped like some of the funky HCI designs (such as the pie ones, or using hyperbolic shrinking); could be sorted by frequency of use; each item could have in very small text the keybound equivalent ('M-Space') - kind of like how Emacs will echo the keybinding of a menu-item if you select it the hard way.
Indeed, it seems to me that there are two "power" interface modes each better for certain tasks or apps: * nearly always keyboard + very little mouse * one hand keyboard + one hand mouse/pen/puck (Laptop touchpads and "eraser nub" pointers complicate matters, too.) Pie menus combined with mouse gestures, while nothing new, could be fun and sleek for tasks that already require lots of "mouse" usage. A precursor to the Maya modelling and animation program had a mouse gesture combined with pie menu system that was extremely powerful and efficient. (Probably Maya still has it but I'm no longer in the rendering biz.) Each mouse button modifier keys combination had its own set of configurable (N,S,E,W,NE,SW,SE,NW) actions which could optionally be another pie menu, iirc, (although some combinations were reserved when engaging in a certain operation.) For example, a stroke with button1 button3 ctrl and alt all held down gave sculpting operations. The action or mode got selected on button release, so running the interface became a quick series of mouse strokes with occasional forays back to the keyboard or numpad. While discussing recombinant GridSelect, yeganesh, Prompt and interface creativity, figured I'd mention there's also a MouseGestures module in contrib -- may as well throw it into the soup, too. -- wmw (p.s. Ismael, hope you don't take offense, not ignoring you, this was quick to respond to, will get around to responding to the many ideas in your threads soon.)