[Haywain]

Private trackers, especially private niche trackers, have far more obscure and interesting content than any single release group or TPB. Private trackers are full of very dedicated users that will go far and beyond to fill even the most absurd and rare requests.

The difference between private and public trackers is quite literally night and day, in terms of both content and security.

Also, there is Usenet which is great for quick release and sometimes rare stuff but had been hammered by the DMCA recently.