Please browse my gallery and let me know if I ever even came close!
In reality...none. They are all a selection of images which mostly suit as wallpapers [backgrounds to a desktop], not images specific to an OS/Computer logon screen.
When logons included skin components for the Users panel etc. [pre Vista] they were 'genuine' skins, not a single wall image applied behind whatever default OS logon panel/details.
They are now [in Vista and 7] frustratingly 'simple' one-image backgrounds.
An idea 'might' be to create a background that has graphics/details pointing to the user logon 'bits' applied by the OS. The issue there is they'd be specific to however many users were listed/shown.
In 'simplistic' terms a Logon 'could' have some dopey message saying "You are logging on to Win7 64" - whatever.
What Snowman's saying is that the post-XP logons really are nothing more than a wallpaper [if that] ...