I already have a system for arranging windows, but it's not based on tiling. My secondary monitor is for cascaded windows, such that the bottom-left corner of every window is aligned along a diagonal line. This makes window switching a spatial experience. As to keyboard power user, I generally exclusively use the keyboard when I'm using an IDE, terminal, email, Google reader, etc., but use mouse for documentation, web browsing, etc.

Two monitors comes into its own when you need to see more information on the screen at once. In my IDE as it is, when e.g. debugging, I have loads of tiled information displays, between the source, disassembly, CPU and FPU registers, CPU stack, memory, symbolic call stack, watches, locals, loaded modules, breakpoint list, thread list, log, project layout, etc. Fitting all that into 9" would be unreasonable; add in the actual running program in a terminal window, and scanning logs of previous runs in less, and it's hard to get by without two screens.