I received an e-mail from the folks at Mar y Selva (hotel) who were evidently motivated by community interest to share something useful that they had found. 

We invite you to the new site http://www.thebusschedule.com know where you can find a variety of schedules of Costa Rica. You only have to indicate the place of departure, the place of arrival, the date and time of travel and all routes including transfers for the trip are indicated. We invite especially all tourism-related businesses to use our pages to actively advertise their business or to help their clients to find the optimum of these connections. Also we are very grateful for any corrections, suggestions or new idea.

I hope that you find it useful as well.

Ben