If you know everything there is about the 'show about nothing' then your first stop should be Sporcle online Seinfeld Trivia. There are plenty of great quizzes to play where you can name the Seinfeld characters or famous Seinfeldisms. If you're a truly hardcore fan, you could try and recite George Contanza's Marine Biologist speech from memory or name all of the strange Fictional Movies present in the series. Either way, if you're a fan of George, Jerry, Elaine and Kramer, you need to spend your days at Sporcle.com