I do, and all my passengers must wear theirs, or we don't move. And I have kicked someone out of the car for not wearing theirs (same parking lot, so I took them to their car).
That wearing seatbelts save lives is (not quite) indisputable (numerous studies in numerous countries indicate this, most of the dissenting opinions simply fail to take into account important but not obvious variables, such as behavior). In fact, studies show that people not accustomed to wearing seatbelts tend to drive substantially more aggressively when forced to wear them. This has been demonstrated to be persistent behavior. This can actually lead to an increase in dead people wearing seatbelts in accidents.
So it is hard to argue for mandatory seatbelts.
On the other hand, driving is a PRIVELEGE, not a right. At least 50% of the population simply doesn't get this. There is no "self-evident truth" that man has the "right to drive whenever, whatever, wherever, however he pleases". It is a privelege (ostensibly) granted to those who display the aptitude for reasonably piloting a vehicle. Since it is such a useful mechanism for transportation, the roads system is paid for with public funds. I have no problem with this, as 100% of the population (even those who do not themselves drive or ride - even the Amish make use of public roads) relies on this system in some way.
The problem comes when people misuse this great privelege. "Your right to swing your fist ends where my nose begins" is a fundamental (though seemingly lost) tenet of the constitution. In order to exercise use of this privelege, most people are required to carry insurance, and be licensed to operate the vehicle. MY insurance goes up when some idiot dies or gets maimed when not wearing a seatbelt. MY insurance goes up when you jump the median, hit me head-on, and your passenger flies through your window. MY family gets injured/killed when you/your passengers fly through both our windshields.
In a given demographic, everyone has roughly the same odds of getting in an accident. People who don't wear their seatbelt are a higher statistical risk for causing harm to others. They should pay their own damn insurance rates. Get caught without a seatbelt but you are in the "wears a seatbelt" rate? Insurance adds the difference you should have paid in premiums to your deductible for that incident, and bump you into the appropriate category, from which you may never go back (seeing as there's no way to prove you have started to regularly wear your seatbelt).
Heck, I would totally support this system, if for nothing else than the Insurance Companies, with their bottom line on the line, would be sure to get the statistics right, and these kind of arguments would cease...
One last thing, to argue that seatbelts are in any way dangerous is specious at best; I don't avoid eating food because of the choking hazard, the odds of surviving without the food are substantially worse than the odds of choking. Everything we do in life has some level of intrinsic risk...