How to create a new user without password

I have google the subject all time, saying I can do with a line: useradd
But the new account is disable and need the complicated password to enable, why? how?
openSUSE 12.3
Gnome 3,6.2 with Fallback mode

I dont think this is possible without using some hack and tricking the system into accepting a blank password. Reason obviously being that Guest accounts with no password/key authentication at all are a security risk.

I think best is to create it the normal way using YaST > Security and users > Users and Groups.

Then afterwards, as root, you use the passwd command for that user, setting it to blank (hit Return). There still is a password to be entered, but it is emptty, thus Return must be enough.

I dont think you can use passwd by itself since you will get an error like this:

linux-n5jp:~ # passwd bob
New password: 
BAD PASSWORD: it is WAY too short
BAD PASSWORD: is a palindrome
Retype new password: 
No password supplied
passwd: Authentication token manipulation error
passwd: password unchanged

Instead you have to use

passwd -ud <username>

I see that passwd has changed a bit since I used it for this sort of tasks. My fault, I should have tested it.