Lock Screen Customizer is a new software by Winaero. It allows you to tweak and extend the options of the Lock Screen in Windows 8. It has nice UI with live preview of the changes you made:
It allows you to change the following options of the Lock Screen:
time format (12/24 hours)
color set for sign in screen;
add Lock Screen Slideshow with autochanging background images every time you sign in.
enable verbose logon messages (see video below);
disable Lock Screen.
While some of those settings like background image or color set are available via the Modern Control panel of Windows 8, others are inaccessible and have no user interface.
Lock Screen Customizer tries to fix this and provide to you options to take the full control of your Lock Screen.
For example, you can change the background image of the Lock Screen. However, when you sign out, you will see not your image but that green Seattle picture. This is the "default" Lock Screen, which has no customization options!
With help of Lock Screen Customizer you will be able to apply all your preferences to that default Lock Screen.
Lock Screen Slideshow
Lock Screen Customizer has a nice feature that I called as "Lock Screen Slideshow". If enabled, it will change Lock Screen background image every time you sign in. So every time you logged in you will get the new image at Lock Screen.
You can also enable this feature for the default Lock Screen, so it's background will be also changed with image of your Lock Screen.
Lock Screen Customizer supports both Windows 8 x86 and x64. It is portable, freeware and supports multi-language UI.