You could find kindred spirits of any interest available for text-based correspondence and enlightenment. I solved countless software problem (including both Windows and Linux) by searching through these groups. Who could forget groups like
Oh, and the flame wars! (I remember there was a character outraged over the Ottoman Empire who sought to cancel every post containing "turkey", which swept up Thanksgiving recipes, as well.)
The beginning of the end was when Web access took off, epitomized by "AOL newbies" pouring onto Usenet without regard to the collegial etiquette that previously existed. After AOL, there was overwhelming growth of users, which strained the scalability of worldwide discussion forums. Finally, the death knell: Spam. When I peek at Usenet groups today, they're full of the most crude and amateurish spam. It appears that posts are not run through filters as is all of our email, and this makes the noise/signal ratio unbearable.
R.I.P., Usenet. You were one of the forefathers of what we enjoy today through the Web, forums, IM, and social networking.