In his three-piece suit and neat goatee, Vinton G. Cerf hardly fits the wild-eyed, unkempt image of a brilliant scientist. But few inventors can hope to see their work so widely used. Cerf, the co-inventor of the Internet as a computer scientist at Stanford University, spoke at the Inventor of the Year award ceremony Tuesday in downtown Buffalo. Now reaching its 30th birthday, the Internet has grown far beyond what Cerf and co-inventor Robert E. Kahn imagined.