Okay, this is my first time viewing this thread, and I don't have the time to view all 27 pages of it, so I apologise in advance if anything I say has been brought up before. I just figured I'd put in my own two cents on this matter.
Overall, I'm for the legalisation of marijuana, basically for the same reasons as a few other people have pointed out. First of all, it's less addictive and produces fewer harmful side effects than alcohol and tobacco and many prescription or over-the-counter drugs. Secondly, legalising any drug reduces the crime rate and makes prisons less crowded. I will also point out that quite frequently, black-market versions of a drug are more dangerous than its legal counterparts. You never know what might be mixed in with them (I've heard of weed being laced with things like PCP without the customer realising it, for instance). It's harder to trust the drug's quality--it might be inadequately stored, for example. In this way, legalising any drug makes it overall safer for use. Marijuana is no exception to this.
And now I will present a couple of marijuana mythbusters that may or may not have been brought up in this thread before. One, THC isn't its only active ingredient. There's also cannabihydrol (something like that; I don't quite remember the exact name). While the former is thought to promote psychosis, the latter actually prevents it, counteracting this effect of THC altogether.
Secondly, I've heard evidence supporting the fact that marijuana can actually promote lung health, even when smoked. I know a couple of people who started smoking it in hopes of curing their asthma, and they never had an asthma attack since. To cite a more personal example, I've actually found it easier to breathe after smoking pot for a while. I think it made my throat more sensitive, but that's the only bad thing it seems. I also happen to like the smell of pot smoke for some reason.
Third, let me emphasize this fact: smoking isn't the only possible method of marijuana use. It is arguably the easiest and quite possibly the most popular method, though. But it can also be ingested, vapourized, and even applied to the skin as a lotion or patch! So anyone who cites smoking hazards as a reason why marijuana should stay illegal is making a moot point.
I also agree with what people have been saying about differences between being drunk and being high. True, both alcohol and weed affect the brain. But they affect different parts of the brain, and in different ways. Ethanol and THC are very different molecules, so they interact with the synapses between specific neurons in very different ways. The two sensations might feel similar to some people, but they are by no means the same.
Oh yeah, and that brings me to another point, which was at least brought up on the first few pages: it affects everyone a bit differently. Just as there's a wide variety of ways people act while drunk, there's a wide variety of ways people act while stoned as well. Some people act retarded. Some people are very peaceful and relaxed. Some people freak out and have hallucinations (which are mild compared to those caused by other drugs like psilocybin and LSD, I might add). Some people act more philosophical/spiritual than usual. Some people feel a strong urge to pig out on junk food. It really depends on the person. Self-awareness of a drug's effects is very important in its use, and that's what many people seem to not get. If you try it and have a bad experience, it's probably not for you, and you shouldn't get on other people's cases about it unless they're clearly doing harm to others while under the influence. And did I not mention that this thread talks about a drug that in most people prevents people from doing harm to others?
That brings me to my next point: driving stoned. Based on my personal experience, it's safer than driving drunk. Why? Marijuana doesn't impair judgment in quite the same way that alcohol does. (Alcohol is a depressant, after all.) So it's easier to judge whether you've smoked too much. It is possible to focus properly while stoned, but in some cases it takes quite a bit of willpower. At least that's been my experience anyway.
I'll never forget the time when I smoked pot with some friends, and afterwards I remembered that I was going to take some guy on our first date. Despite the fact that I was quite high the whole time, the date went smoothly, I was able to drive with few problems, and my date didn't even notice anything wrong with my behaviour. However, while I was driving, I took extra precautions to assure that I was being safe and focused, being more careful than I normally am. Oh yeah, and there was another time when I drove on a winding mountain road while stoned. During about half of the drive, a cop was following me, but he never pulled me over. Now, I'm not saying that driving while stoned is perfectly okay. I'm saying that it's just possible, as long as you use good judgment beforehand and do it in moderation. The real problem with people driving under the influence of anything is that they could make stupid mistakes if they're not careful about it and don't know what they're doing.
Also, I LOL'd at the proposal that using medical marijuana for anxiety disorders can cause panic attacks. I'm not quite sure how sound that evidence is, but I can see it happening in some people. I think the main reason why I LOL'd was because I myself am using medical marijuana for anxiety issues, and have never experienced a panic attack before. I have had minor freakouts when I smoked a little bit more than I had intended, but after sobering up I always felt happy and relaxed. Of course, that's just my experience, so take it with a grain of salt.