TIB – Ibiza public transport. Bus, Disco bus, transport cards and fares - CIE
eivissa.tib.org
Public transport in Ibiza: routes, timetables, transport card, maps, fares, customer service, stops, news and notices.

Just saw that the Bus website for Ibiza has been updated and is a bit more helpful for those visiting the islands. Available in ES, CA, EN, FR, IT, DE.