What are my options for centralizing Unix user management

view full story

http://serverfault.com – We have 15 Debian servers and growing. What's a simple, lightweight method for centralizing user management? Use cases would be adding a user across all servers, tweaking a users access on a specific server(s), removing a user from all servers. LDAP is an option but seems too full on for my needs. I'd rather something with the simplicity of useradd/groupadd, just spread across multiple machines. Web interface would be nice but not necessary. Git interface could be really cool. (HowTos)