Marketing is a lot better when it just 'happens' though.
Google wasn't marketed, they didn't start selling books about the right way to make a business, they just made something good and watched as people started using it.
Back in the day Larry and Sergey accepted every interview they were approached for and hammed it up all over campus posing for photos standing on balls and playing with toys in order to keep that "wacky geniuses" thing going and get on all the magazine covers.
Once they found a business model and could hire enough programmers to basically churn out a new feature/project every week, they had built-in marketing and enough brand to self-sustain itself.
Are 37signals already to that point? I don't know, maybe, but faulting a 10(?) person, self-sustaining, Chicago company for keeping their name out there by comparing them to a grow-as-fast-as-possible, well-funded, Valley startup-gone-gangbusters that's been the feather in the web's crown for the past 10 years is a little unfair.
Really? Because they avoid advertising themselves beyond their blog. Is writing a really good, useful blog self-promotion? If so, it's not the greedy sort that the terms "self-promotion" implies.
I'm at a loss to know what they could say in a 'university' that they haven't said already.