I'm a huge fan of Mitfahrgelegenheit. I don't know if I've explained this to my beautiful friends at home yet, so I will proceed:
Mitfahrgelegenheit is essentially the same premise as CouchSurfing, except instead of a place to sleep, people provide others with transportation. Actually, the mission statement of CouchSurfing has something to do with bringing the world together, and I don't think Mitfahr is that ambitious. CouchSurfing is also free. Hm. Anyway, what actually happens is that you hop into a stranger's car and hope for the best.
The first time I used this website, I rode to Baden-Baden with four other people. No one spoke to each other, and the guy was a relatively safe driver, I guess, but only because nothing bad actually happens because of speed alone. I drove with the same dude on the way back from Baden (a strange coincidence), and he beckoned me into the front seat and we talked for about an hour. After I had the realization that he was kind of boring, I had an even more paralyzing realization: when you've started a car ride talking to the person next to you, there's no real good time to put your headphones on.
Last time, I drove to Berlin from Konstanz with two of the hugest stoners ever, who listened thrice to the same Police album. Thrice. Thrice, we almost got into accidents. Thrice, the guy in the passenger side screamed, "AAAAAALLLLLLTTTTTAAAAAAAAAAAAAAAAAA".
Sunday, I'm going to drive with another dude. I think he's Turkish, but I couldn't tell exactly from his accent. Excitement will hopefully not ensue.