Mac OSX: Keep window on top

Does anyone know a way to keep window on top in OSX? I've tried Afloat and works with about 15% of the apps out there. I know that you can snap windows to different corners but I often need to be able to keep one window (IM for instance) atop of another. I can't believe there isn't "pin window" functionality in OSX, natively or third-party. Thanks!

Unfortunately, it is against Apple's Human Interface Guidelines, ever since pre-OS X, MacOS 8 and even pre-System 6 and 7 (see the Original HIG PDF). Even modal dialogs were/are frowned upon. Hence, the difficulty.

The same question has been asked on SE Ask Different - see Any nice, stable ways to keep a window 'Always on top' on the Mac?

There is a successor to Afloat called Fenêtre

Also have you considered a tiling window manager such as Amethyst?

This dynamically resizes windows so they are always visible and take up a certain portion of the screen.