I use always-on-top.exe[1] on windows
One feature I would really like is the ability to lock a window to a region of the screen and allow other windows to be snapped around it.
Firstly you should be able to snap a window into the four corners by pushing the mouse into the corner for x seconds. (like ctrl+alt+numpad 1, 3, 7, 9)
If you had a window locked to the right side of the screen you could still snap another window to 50% of what's left. And if you manually re sized it to be small be able to snap another window to be 50% of the screen space that is left after two windows have been locked.
If this is possible please let me know.
1: http://www.labnol.org/software/tutorials/keep-window-always-...