If you have to take the bus, it had better be cheap, right? Newcomer Megabus.com, which launched in spring 2006, takes that attitude seriously. So seriously that it offers a limited number of $1 bus fares on each of its routes.
The company characterizes itself as an express intercity line and serves a number of Midwestern states from its Chicago hub. Megabus.com now serves California, Nevada, and Arizona as well.
I did a quick comparison among Megabus.com, Greyhound, and Green Tortoise between Los Angeles and San Francisco. For a ride next week, Megabus didn't have any $1 fares left, but the one-way price was $10. Greyhound had tickets for $39, and Green Tortoise—with its lounge area, bunk beds, and stereo system— was $39, but runs only on Sundays and only from L.A. to San Francisco (on the way south, the bus heads from San Francisco to Las Vegas).