How can I handle a .org domain on my own nameserver without paying for unwanted services?

view story

http://serverfault.com – I have a dot org domain that I use to run a website. Until now, I had an account onto a hosting+domain provider. Recently I thought to run the website on my own webserver and to handle the domain on my own nameserver. What do I need to do in order to handle my .org domain by my own? Do I still need a registrar? Is there a more direct way that pir.org provide in order to fill in just a nameserver to be bound to a domain name? (HowTos)