I don't drink (alcohol or coffee) and I don't smoke, but I'm still for legalization of marijuana. Some people have brought up the point already that the experiments that were conducted which shows how harmful marijuana is were improperly conducted. In fact, I believe one of the early studies which shows it causes brain damage was ruled as being properly conducted by the AMA themselves. However, no one brought up the fact that marijuana/hemp is quite a useful plant. It can be used to make fuel, which would help with the rising gas prices, lessen dependency on oil exporting nations, one acre of hemp is worth 4 acres of trees, since hemp can also be used to make paper, and building materials, rope, ect. Check out these links:
http://www.hempnet.com/
http://www.hempnation.com/
http://www.marijuana-hemp.com/
Hemp doesn't require pesticides, and can be harvested 4 times a year. Hemp gives more fiber than the cotton grown in the same amount of land, and it can grow in even poor soil, enriching it. By the way, hemp was the original name of marijuana in the English language, it's also known as cannabis from Greek for canvas, which hemp can be used to make. The name marijuana is the Spanish version of the same plant and was popularized by a guy who started calling hemp by that name to associate hemp with the Spanish thereby feeding off some Americans' predjudice of Spanish people in a campain to outlaw hemp. Why you ask? Well as previously stated, a lot of items can be made from hemp (with no toxic waste, ie paint, as opposed to the processes which currently exist, many of which do leave toxic residues) which would have competed with a certain other chemical company's processes. This same man who owned the newspaper was involved with the chemical company somehow, I forget, perhaps it's in one of those links or you can do some research on your own.
Gateway drug? What about the Netherlands? It's legal there and drug use is lower. Doesn't quite prove the gateway drug theory.
Oh, one other thing, a while back, some Asian countries tried to ban tobacco, making it an illegal drug. The tobacco lobbists did there thing in Washington and lo and behold, the US threated a trade embargo if tobacco was banned, afterall, the US need that extra cash from exports. Now take the same thing with other countries importing marijuana, suddenly we have a war on crime where the US must protect it's poor citizens who don't have the brains to make their own choices from this dangerous drug, but tobacco is ok.
Eh, I'm starting to ramble now, so go forth and do some research before just spouting things anyone, even myself, told you. Just so long as the research doesn't involve you smoking any bongs. I may be for legalization of hemp, but that doesn't mean I would approve of people using it to smoke if they don't have a legitimate medical reason to do so, especially around me.