There's been a few documented incidents of passengers getting killed or seriously injured during turbulence, so the belts actually are useful. Turbulence is actually not dangerous at all as an aircraft is designed to shake and flex under strain, with the wings able to withstand up to a 45 degree bend before snapping, which would never happen due to wind. It's just very annoying. In fact, I recall one flight on an MD80 where I was sitting towards the back and literally could see the front end bending heavily in
I use the following two sites most as a frequent flyer. One tells you in detail which seats are most comfortable based on aircraft type and the other has interesting tid bits on safety, including fear of flying , which supposedly affects 1 out of 3 Americans to some degree. As a frequent flyer, I dread the summer months most. More delays and more passengers, with kids. Lots of kids.
http://www.seatguru.com/
http://www.airsafe.com/