1) The fact that in SF and NYC, they charge directly per listing in certain categories.
2) The fact that they didn't take VC funding.
3) The fact that they stayed small.
4) The fact that they didn't sell the company.
All of these would have been extremely easy to stray from, but instead they stuck to the core philosophy. What DHH was talking about was just that: a philosophy. Any company can stick by that philosophy, regardless of how it attracts customers or the specifics behind their product or service.
Asking the question "what other web or software companies make a living the 37signals way?" is kind of a weird question. The 37signals way is actually the normal way to run a business. It just seems weird because the scale of the web has thus far screwed up everyone's minds to the point where everybody forgets the past.