Despite his mediocre political credentials and undistinguished academic record, Thomas rose from junior Senate aide to Supreme Court justice in less than a decade. Here's the parade of plum positions that he got: assistant secretary of Education for civil rights, chairman of the Equal Employment Opportunity Commission (EEOC), an appointment to the federal judiciary, and of course, Supreme Court judge. His quick rise up the political and legal ladder was all preceded by his race based admission to Yale Law School. 
Clarence Thomas is a Supreme Court justice. He was appointed after by Daddy Bushes when Thurgood Marshall stepped down. Marshall should have waited four months, Bill Clinton would have been President and Marshall's great work with the NAACP might still be intact. Surprisingly Thomas is extremely Conservative. 
Helping other blacks
As far as Liberapedia knows , Clarence Thomas has never joined on any opinion that would actually help African Americans. Instead, as a great scheme to help White, Rich Conservatives, he has advocated against Affirmative action. Interestingly, he grew up Poor and suffered Racism from the exact kind of elite rich white snobs he works with.
[Thomas] is the court's only African American, and it's most conservative member. He is arguably the most influential black man in the country, yet he is reviled by many in his own race for his opposition to government programs intended to help minorities. 
According to Slate some accusations frequently made against Thomas are justified but not all. 
Virginia Lamp Thomas
His wife Virgina Lamp Thomas has a conservative organization Liberty Central. They've got a long list of donors asking Clarence for favors.
Thomas has been accused of sexually harassing Anita Hill but according to Wikipedia this was never proved.