Exposé clones for Windows:

Switcher  free   req. > Vista +Aero, Win7  ?
http://insentient.net/
http://insentient.net/Switcher/Overview.html
Related
http://anterence.blogspot.ca/2011/01/expose-for-windows-7.html

SmallWindows ,  Free
http://smallwindows.sourceforge.net/  free

DExposE2   Free
https://sites.google.com/site/devrexster/dexpose2

Mac Expose for Win7  Free
http://revengexx14.deviantart.com/art/Mac-Expose-for-Windows-7-271013760
This is a program from Microsoft that's very similar to Mac's Expose. Unfortunately it only works with the Microsoft Touch Mouse but it's a freaking great program. It's part of IntelliPoint, and I'm hoping it'll work natively in Windows 8.

DEXPOT  Free
http://dexpot.de/

WinExposé   Free
http://www.matiasmoreno.com.ar/en/WinExpos%26eacute;


Shareware:

Better Desktop Tool.  Standard $9.99 Pro$ 19.99
http://www.paulspoerry.com/2013/betterdesktoptool-desktop-customization-exopose-space/
http://www.betterdesktoptool.com/buy_promo.html 
  Reduced price until 28-Feb-2013   Standard $7.99 ; pro $14.99
http://www.betterdesktoptool.com/index.html
http://www.betterdesktoptool.com/features.html

TopDesk  $19.95   XP , Vista,W7
http://www.otakusoftware.com/topdesk/

DeskPose 2D   $19.95
http://www.thinkinbytes.com/en/products/deskpose/