The topic of filters for protection hasn't been aired on Talk Photography for a while. I might bring it to the fore for a chuckle after today's event. How I managed to drop my D90 onto my slate fireplace, albeit from a less than two feet, I really don't know. It just slipped from my grasp and landed with a horrible crunching and cracking sound. I fully expected it to be dead. All that appears to have happened is that the filter ring got a severe denting and the filter glass cracked.
There's a slight chip in the plastic of the lens barrel, but very superficial. There were a few small shards between filter and front element, but no damage to the element itself. That seems to be it. The camera appears to function normally and the lens autofocuses. It took a bit of effort, and some cycle inner tube to provide extra grip, but the filter came off okay and a replacement has been bought and fitted.
I can't say for sure what would have happened had the filter not been in place, but the threaded part of the lens barrel would certainly have taken the brunt of the fall and suffered far more damage than it has done. They seem to build Nikon's tough. For all the plastic construction this one has already survived sliding off the passenger seat of my car when I braked suddenly, and mysteriously rolling itself off the sofa. I'm sure I'll manage to kill it eventually!