The last time registration opened only for a few hours, so if you do not have an account on this NZB site I suggest to register quickly. New members receive a 30 day trial period. After this time, you can still use DOGnzb for a $10 fee. Given the popularity of the site and the scarcity of invitations I propose to take account in your budget.
DOGnzb needs no introduction. Fall Newzbin and NZBMatrix caused the DOGnzb became the only such good NZB service. This is probably the best place to find what is interested in usenet. And it is almost impossible to get there beyond such occasions as this.
Visit their registration page to sign up.