I have always like Ball Pythons. They are relatively cheap, easy to keep, and are not very aggressive. Kings and rats are also good suggestions. I would stay away from any of the bigger snakes though if you are just beginning, particularly retics and burmese pythons. Many pet stores will sell them for cheap and market them as easy to keep, but it's quite the opposite. They get HUUUUUUUUUGE and are very dangerous, especially if you don't have much snake experience under your belt. I don't think people have any business selling these snakes.
Also, like lovespunaround said, just because they are easy to keep and less demanding doesn't mean they can be neglected. Good luck though! IMO snakes can make great pets and are really fun to keep.