Tony Miller is a classic serial entrepreneur. His new company, Bind Benefits, offers “on-demand health insurance.” The concept calls for enrollees to be able to add benefits beyond core coverage as needed. Miller was co-founder and CEO of Definity Health, which started in 1998; UnitedHealth Group acquired it for $300 million in 2004. He then founded Carol Corp. in 2006 and led it until its sale to UHG’s Optum. He’s also managing partner of Lemhi Ventures, a health care-focused venture capital firm (and Bind investor). In June, Bind announced it had raised $70 million in financing. Some big players clearly have faith in Miller: Bind’s backers include UnitedHealth.