Dave Chappelle has signed a massive deal with Comedy Central that will return the comedian's hit series to the network for two more seasons. Sources familiar with the deal indicate it could be worth about $50 million, vaulting Chappelle, 30, into the rarefied realm of television's top earners. The new contract is believed to mark not only a steep increase for Chappelle as star, writer, co-executive producer and co-creator of "Chappelle's Show," but more significantly, reward him with a hefty chunk of the series' robust DVD sales. Increasing the pressure on Comedy to close a megadeal with Chappelle was interest...