There is a little known visa known as an O1, for 'extraordinary persons'. This is the visa that many foreign founders obtain. One is allowed to found and work for a company in the US while one is on it. I think they last 3 years.
Generally, PhD level people can obtain it, though it is a pain to do so. I have heard of people straining to get 10 eminent people to write supporting letters for one's visa petition. A good link is here:
http://www.hooyou.com/o-1/faq.html
There's a fairly extensive list of what may be accepted as supporting documentation there. I think these are the criteria the government uses:
Receipt of a major, internationally recognized award, such as the Nobel Prize; or at least three of the following forms of documentation: (1) Documentation of the alien's receipt of nationally or internationally recognized prizes or awards for excellence in the field of endeavor; (2) Documentation of the alien's membership in associations in the field for which classification is sought, which require outstanding achievements of their members, as judged by recognized national or international experts in their disciplines or fields; (3) Published material in professional or major trade publications or major media about the alien, relating to the alien's work in the field for which classification is sought, which shall include the title, date, and author of such published material, and any necessary translation; (4) Evidence of the alien's participation on a panel, or individually, as a judge of the work of others in the same or in an allied field of specialization to that for which classification is sought; (5) Evidence of the alien's original scientific, scholarly, or business-related contributions of major significance in the field; (6) Evidence of the alien's authorship of scholarly articles in the field, in professional journals, or other major media; (7) Evidence that the alien has been employed in a critical or essential capacity for organizations and establishments that have a distinguished reputation; (8) Evidence that the alien has either commanded a high salary or will command a high salary or other remuneration for services, evidenced by contracts or other reliable evidence.