Culturally, textfiles.com would probably be at the top of the archive game. Jason Scott puts a lot of effort into preserving that sort of thing, and would probably be happy to sell cheap media through the mail with content on it.
The way I'd see it, there'd probably be a few networks. There's obviously a lot more wireless devices capable of ad-hoc transmission then before the internet was popular, so there'd likely be some sort of meshnet-esque way of communicating.
There'd probably be a lot of inventive ways of using the phone network as well. For data, I'm sure there'd be a lot of study into powerful compression and modulation techniques (you'd be surprised how much you can cram into an 8 khz PCM channel), but also some pretty extensive use of conference calls. Not like, the shareholder meeting type, but semi-commonly, you'll see people use conferences just to joke around with each other, and collaborate on things; there'd probably be a good deal more of that.
What network someone picks would probably depend on their personal values and social circles, but just from observing Reddit, I feel like there'd be a lot of people who might feel like a fish out of water without internet - particularly among younger age groups. It's likely there'd be walled gardens set up by companies looking to capitalize on people feeling lost.
Ultimately though, people are resourceful. As a species, we've survived through a lot worse then a lack of internet access. For what we lack in physical literature, there's bound to be someone ambitious/smart enough to either reverse engineer something in place or come up with a new solution to their problems. East Germany's Poly Play arcade machine is a good example of this.