Somehow we missed the news that UK-based Megabus.com (which began its first service in the U.S. in Chicago in 2006) began running low-cost bus service between D.C. and New York on May 30. We spotted this Megabus bus stop sign outside Metro Center on Friday. Much like relative newcomer BoltBus, Megabus.com offers tickets as low as $1 if you book early enough, as well as free wireless internet on board. Looks like they actually…