Worst I ever had was in the fall of 1996. I had flown down to Tampa to spend a few days with my uncle and to go over to Disney for an audition. The day I was flying home, the north east coast was being hit with an early Nor'easter, though it was too warm for snow.
I was flying from Tampa to Newark, then on to CT. We tried landing twice in Newark, but the weather was just too bad. We were getting tossed left and right, and dropping in ten to hundred feet dips. After two attempts the pilot had to divert to Philadelphia because we didn't have enough fuel to keep circling for another attempt.
Once in Philadelphia we sat in the plane for an hour or so and finally the pilot managed to get us a gate so we could get off, waiting for the weather to improve. We were told that we were going to head back to Newark as soon as we could, so if anyone didn't come back on the flight the airline wouldn't be responsible for their expenses to get themselves home or to get another flight.
About an hour later we got back on the plane and headed back in the air. About half the plane (no exaggeration) did not return. We headed back to Newark, and the pilot managed to earn his $120k/year on that landing, in my opinion. It was the most terrifying flight I've ever experienced, I honestly felt like there was a good chance we would crash during it. Those of us who were left cheered.
Oh, and then I got to take a puddle jumper from Newark to Hartford, which wasn't quite as bad as the weather had broken a little bit. But I got to Hartford around 10PM and my mom was supposed to pick me up, but it was snowing and she didn't want to drive the 2 hours in the snow to get me. (And I didn't blame her.) So after all that, I ended up spending the night in the airport as well.
I'm not AFRAID of flying, but turbulance puts me on edge a lot more than it used to. It wasn't until having to endure a 20 hour flight to and from Hong Kong last year that I've started to not be bothered by it as much anymore.