Deviant Art is a good source for all custom extra plugins and wallpapers.
One Deviant Art user “mufflerexoz” has created a Windows 8 theme for Windows 7.
The Windows 8 theme provides lots of new features along with a newly designed interface. It looks very similar to Windows Vista and Windows 7(Great combination) but there are many GUI changes like redesigned taskbar, Explorer, new boot screen and login screen, etc.
Check out the link below and download the themes,Logon screen,Wallpapers,System Tray icon, Tclock Lite & Watermark.
Windows 8 Transformation Pack