Ubuntu 11.10's default display manager, LightDM, is definitely a piece of software with a great potential of customization, development and growth.
Robert Ancell, LightDM's creator, has just launched an awesome 3D greeter, Crowd greeter, which acts, looks and feels like a 3D character-based video game, and, basically, consist of a 3D model walking on your screen with your name on it.
To actually log in, you have to click on the "your name" character (when you hover the mouse over the character, it stops walking) and type your password.
How do we install LightDM's Crowd greeter?
Add the following official PPA (Oneiric)
sudo add-apt-repository ppa:lightdm-team/crowd-greeter
sudo apt-get update
sudo apt-get install crowd-greeter
sudo gedit /etc/lightdm/lightdm.conf
and set greeter-session=crowd-greeter (you just need to enter crowd instead of unity)
To remove the Crowd greeter
sudo apt-get install ppa-purge
sudo ppa-purge ppa:lightdm-team/crowd-greeter
From the developer page: >"DO NOT BLAME ME IF YOUR SYSTEM BREAKS"