SaaS as a business model, not as a technology. Webmail was a feature, not the entire business, for the most part. I'm sure you can find examples of SaaS before

SaaS as a business model, not as a technology. Webmail was a feature, not the entire business, for the most part. I'm sure you can find examples of SaaS before 37signals, but that doesn't detract from the fact that they were amongst the first to build an entire company from the business model.