These are some of my long time favorites, and it would be truly awesome to see any, much less all, of them updated for Windows 7. Similar updates for each for IconPackager would likewise be sweet.
http://www.wincustomize.com/explore/windowblinds/3886/ (My Matrix 2 by Xav73)
http://www.wincustomize.com/explore/windowblinds/4605/ (My Halloween by Xav73)
http://www.wincustomize.com/explore/windowblinds/3702/ (Christmas Time by mormegil)
http://www.wincustomize.com/explore/windowblinds/4881/ (Mac OS X Tiger by Steve Grenier)
http://www.wincustomize.com/explore/windowblinds/5111/ (Tiger 2 by Kol)