I'm going to Costa Rica and want to take advantage of the country's bus 
services.  What resources can I turn to help me plan my journey?

Costa Rica has a very efficient and expansive bus system. World Headquarters' 
website has this to say about it:

http://www.worldheadquarters.com/cr/transportation/
"Costa Rica's efficient and elaborate bus system provides the most inexpensive 
and popular method of travel throughout the country. The vast road system makes 
virtually every region of Costa Rica accessible by bus. Recently, several 
transportation companies have acquired more modern, air conditioned buses for 
use on long trips, or for the most frequently traveled routes. Most bus service 
in downtown San José, as well as in the countryside itself, however, relies on 
older more conventional style school buses. For the most accurate bus 
information, visit the ICT office in San Jose, as detailed bus schedules and 
maps are readily available.

From San José, all buses depart either from terminals or from streetside. 
Depending on your destination and time of travel, we recommend that you arrive 
early to purchase your tickets, particularly during weekend travel. The most 
popular destinations have hourly departures. The newer, more modern buses have 
concealed storage space, along with compartments overhead. Older buses provide 
little, if any, storage space for your belongings, aside from your lap. As 
always, travel lightly and keep an eye on your belongings, especially during 
rest stops and scheduled stops.

Generally speaking, the bus system is quite organized and runs close to 
schedule. However, cramped seats, pot-hole littered highways, dusty dirt roads 
and the unanticipated breakdown should be expected."

Costa Rican Bus Schedule
http://www.exintur.com/costarica/hopon.html

For information about hotels, transportation and National Parks, visit 
http://www.hotelstravel.com/costarica.html

For information about hotels, visit 
http://www.amerisol.com/costarica/lodging.html

For more breadth of information about Costa Rica, please also visit
http://www.worldheadquarters.com/cr/
http://www.orbitcostarica.com/
http://www.virtualtourist.com/Central_America/Costa_Rica/?s=v

And of course, the official tourist board has a wealth of information, 
http://www.tourism-costarica.com/tourism-costaricacom/html/index.html

Off to plan my trip to Costa Rica