I'm looking for a website which sums up all bus routes in Poland. If possible some kind of navigator.
Basically, I want to enter my starting point and destination and have the website suggest a bunch of routes.
This might not include private bus operators, but is worth a try: http://en.e-podroznik.pl/
Although this is a little bit old question, but I'll put this answer here for future reference.
My polish friends suggested it to me. I used it in Krakow and Warsaw and it was pretty much accurate, It has all buses and trams table times, and the mobile app has navigation option too.
The bus system in Poland is split based on distances the buses serve: urban (local, city) buses, regional buses, domestic intercity buses and international intercity buses.
Urban and regional bus are well organized, most all information can be found as previously mentioned at jakdojade.com.
Regarding intercity buses, there are hundreds upon hundreds of decentralized bus companies and these are not easy to summarize. e-podroznik.pl is a good summary of intercity buses between two Polish cities, though a few bus companies are missing. The site also has some info on urban and regional buses.
For buses to and from Poland from cities in other countries busbud.com has decent coverage (full disclosure: I work on this project).
You may not find all the routes but busbud.com has departures from Poland and allows you to check buses and book them online.