I'm not a huge fan of buses, myself, but you have to admire Megabus. The low-fare bus line is expanding like crazy. Today's news: Beginning May 30, service is launching between New York and Boston, Washington, Philadelphia, Baltimore, Buffalo, Atlantic City, and Toronto. There will be a handful of $1 fares, though they must be purchased very far in advance, and of course prices go up the nearer you get to the date of departure. After hearing one too many scary tales from the so-called Chinatown buses, I'd certainly be more willing to go with Megabus.
A New England road trip itinerary on a budget
How to find the cheapest Mediterranean cruise and hit the seas for under $200
Road trip the Southwest on a budget
51 affordable discoveries across America