If you are travelling around Europe you may want to check out the Student Agency
bus lines. Some of them are dirt cheap (Bratislava - Budapest = $4.50) and provide quality, multilingual service. They show movies and serve hot drinks. In my experience, the busses have been clean and the seats spacious. This can even be a good deal if you have a Eurail pass because if you do not have an unlimited pass this can save you a day. If you're under 26 don't forget to ask for your 10% discount!
This has been mentioned by raoulduke and I second his opinion, so sticky maybe, mods? =]