Also a good example. 37Signals has great advice here: sell your byproducts. Amazon was forced to invest heavily in scaling dynamic websites as a byproduct of running a high-volume retail store, it invented a lot of internal tools to support that some of which they've adapted and spun-off into standalone products like AWS, EC2, S3, etc. In the process they've helped leverage themselves into more of a technology company than merely a web-store.
This is why it's smart to be a technology company first. It worked like crazy for Bell Labs for generations.