Expose, LaunchBar, Butler on Linux?

[Brett Kirksey]

There are a few apps I have become very accustomed to using in OS X that 
I would like to have in Linux.

Exposé gives you instant access to any open window with a single 
keystroke. Display all open windows as thumbnails, view windows of the 
current application, or hide all windows to quickly locate a file on 
your desktop.

LaunchBar lets you hit a system wide hot key and then just start typing 
the name of any app, document, url, song, etc. and it will bring up a 
list of matching items and let you open the one you want.

Butler has similar functionality as LaunchBar, but I use it primarily 
for its multiple pasteboards. I can cut or copy many items before I 
decide to paste any of them. Then I just hit a system wide hotkey and 
all of my pasteboards show in a pop-up menu for me to select the one I want.

Does Linux have any apps with similar functionality or are any currently 
in development?

Thanks,
Brett