As head of RealNetworks, maker of the popular RealPlayer software and Rhapsody music streaming service, Glaser is one of only a few "40 Under 40" alums who still has his old job.
While his business is still growing, though, the past year has been rough. Last fall, Glaser launched a new service, RealDVD, that lets users copy and store DVD files on their computers. But this summer, a federal judge issued an injunction to ban sales of the software on copyright infringement grounds. (RealNetworks has appealed the decision.)
Meanwhile, his investment in AirAmerica hasn't worked out as planned. A lifelong liberal, Glaser was among the first and most generous investors in the progressive radio network,
but it hasn't become the liberal counterweight to conservative talk radio its founders intended.
NEXT: Pierre Omidyar