I can't believe I didn't see this in the galleries until today. Greenreaper has created a logon pack for Windows Vista that makes use of the included wallpapers on your PC. Vista includes a bunch of beautiful wallpapers, and this pack lets you easily have them as logon screens now.
"Installation instructions: Extract .logonvista files to a directory or to your desktop, then drag and drop them on to the LogonStudio Vista window. Logons should appear at the bottom, under "Built-in logon screens". The .logonvista files can be deleted after install."
To use this pack you need to have LogonStudio Vista (free) installed.
Download: Vista Logon Pack