How about Skippy-XD? It is a full-screen task-switcher for X11 similar to Mac OS X's
From the above site:
Skippy-XD is a standalone application for providing a window picker with live previews (including live video) on Linux desktops that run an X server with compositing support. That means it's not baked into the window manager, and the compositing is not being used all the time. So the performance of you're window manager isn't degraded, but you still get a window picker that's every bit as pretty as OSX's Exposé or KWin's "Present Windows", with all the desktop-navigational efficiency. Compositing only takes effect when you press the hotkey to display the window picker.
I've tried it and it works well, though it doesn't include window decorations.
To install latest development packages (recommended), use the Skippy-XD PPA (daily). If you use
Xfce, you can easily bind
skippy-xd command to Alt + Tab or Alt + Esc in
Settings > Keyboard > Shortcuts. For other DEs it should work similarly.
Binding Skippy-XD to a screen corner
You can use
xdotool to bind skippy-xd to a screen corner. First, make sure
xdotool is installed:
sudo apt-get install xdotool
Add the following line to your autostart applications:
xdotool behave_screen_edge bottom-right exec skippy-xd
Valid location keys are:
xdotool is very lightweight and should have next to no negative impact on your system.
Source for the screen corner binding technique: