It should raise some eyebrows that MySQL AB, the Swedish maker of a free database management system, has sold itself to Sun Microsystems at a price that Cnet estimates at (begin Dr. Evil impersonation) one... billion ... dollars. Hopefully it also will open some minds about alternative business models and "low end" innovation.
MySQL's revenue model is best described as "voluntary pay." Anybody can download and use the software at no charge. Businesses are encouraged to sign up for support services, but that's completely optional.