You want to enable a password less account in Gnome for your family/friends who have access to your computer.
This is different than not typing a password (autologin)
How to - by example
Create a user (system/administration/user and groups)
You can put fancy characters in the real name but not in the username.
You are obliged to enter a password. We will get read of it afterwards.
real name: invité (or guest or whatever you want to display in the graphical greeter later on)
profile: desktop user (DO NOT use administrator)
click ok and close the users and groups tool.
Remove the password for the guest user
open a terminal
sudo passwd -d guest
Authorize login with no passwords in gdm
sudo sed -i 's/#PasswordRequired=false/PasswordRequired=false/' /etc/gdm/gdm.conf
Authorize login with no passwords in pam
sudo sed -i 's/nullok_secure/nullok/' /etc/pam.d/common-auth
You can now log in with your guest user with no password.
If you want a graphical greeter screen, select it in system/administration/login window [local tab] (example: human list)