“Rapiditos” are buses that you can take for really cheap. (sometimes known as chicken buses, although I have yet to see a chicken on one) There are two different kinds that I know of…ones that run within a city and ones that you can take from one city to another. They are usually like a big minivan, but can also be an old yellow school bus.
There’s no real schedule for the ones in town…you basically stand out on the street and wave one down. Apparently there are rutas (or routes), but I have yet to figure those out. For the longer rides between cities there are different levels…those that you sign up to take and those that you wave down from the highway.
So far we’ve taken one home from school for 4 lemps (about 20 cents US) and one of the nicer ones from Tegus to Danli, a 2 hour trip, for 50 lemps ($2.50 US). They are kind of fun and everyone stares at us because we are the only gringos on board!