I am a big fan of 37 signals. This Fast Company story highlights 37 Signal's focus on making a company profitable and sustainable in the long term. I wish a lot more Internet startups took a similar approach.
Pay attention to the number of hours employees work in the story. In popular Internet media, there is a lot of hype about working crazy hours. Working 80 or 100 hour work weeks is not sustainable. The focus should be on building something that will last for a long time.