Bus Eireann run express and local services throughout the country. An Open Road ticket, giving unlimited travel on all scheduled services, costs 45 euros for a pass giving you any 3 days travel within a 6 day period or 58 euros for 4 days travel within an 8 day period. (There are other options, for longer periods, available). You can buy your tickets online: (This link won't be clickable because it's an https, rather than http, URL. Simply copy it and paste it into your browser's address bar):
https://www.buseireann.ie/ecommerce/Coverpage.asp
Cork Airport services are here:
http://www.buseireann.ie/site/airport_services /cork_airport.asp
The journey planner for Bus Eireann services is here:
http://194.106.151.88/bin/query.exe/e
Bus Eireann also run guided tours from Cork (which are not included within the validity of the Open Road ticket).
Easytours run guided coach tours from Cork. (These are only from April to September but they might be of interest if you're travelling soon or planning for next year):
http://www.easytourscork.com/tours.html
Don't forget the trains! Timetables are here:
http://www.irishrail.ie/your_journey/printed_t imetables.asp
or use the journey planner here:
http://www.irishrail.ie/home/
Chris