This little script adds groups and users all at the same time, the password isn't set here;

Users='steve:1001:1001:Steve Jones:adm,cdrom,sudo,dip,plugdev,users,lpadmin,sambashare
marla:1002:1002:Marla Cook:adm,cdrom,sudo,plugdev,users,lpadmin,sambashare
clug:1003:1003:CLUG Admin:adm,plugdev,users'