I used to smoke a small amount of marijuana almost daily to help me sleep and for fun. Instead of laying awake until 6am I could get totally immersed in a movie or tv show and be asleep by 1am. Playing adventure games while stoned is awesome too. Beats a big screen, 1080p60, stereoscopic 3D or surround sound system.
Pretty harmless, haven't used it again after moving to Canada. I don't fall asleep until 3am, not as bad as it used to be. I wouldn't mind using again but am too lazy to find a dealer, coffee shops spoiled me. (originally Dutch)
I've also used xtc for short periods a few years. Usually when going to raves or dance clubs, perfect weekend party drug. Harmless if used correctly, and you need to take long breaks as it loses its effects. It has helped me open up and become more able to talk to other people. It was an therapeutic drug originally, but I only found that out later. It was just a lot of fun. But be careful what you say, your inhibitions to share your innermost feelings are pretty much gone. xtc + trance music + light show = awesome.
Tried speed once. Coded through the night, most productive night ever. But it makes your dick shrink to the size of a peanut. Haven't touched it again...
Magic mushrooms. Mixed experience, first time just a bit of red shift in vision, second time more weird stuff going on like suddenly feeling the ground move, then I got sick for hours. Too unpredictable imo.
Cocaine, only tried a few times. I did not want to get addicted to that stuff but curious anyway. It wakes you up, makes you feel like you can do anything. With us that just translated into playing GT2 all night after the clubs closed.
Cannabis is the most harmless and after your mind gets used to it you need less and less to get into that state of mind. It's not for everyone, some get paranoid, some really can't use the extra calories. Food tastes awesome while stoned! Best is to smoke (water pipe or whatever new gimmicks they have nowadays) for immediate effect, no risk of using too much. It can focus your attention to get totally immersed in music or a movie, shutting out all the other distracting random thoughts. Comedies are way more fun, scary movies are actually frigging scary. It can also show you a lot of how your brain works, especially perception.
No long term side effects, but there is a slight fog like feeling in your head the next morning. Way better than a hangover but there is an after effect. And you might find you left your game saved in a bad spot with 5 health left after running around in circles for what seemed like forever. I guess regenerating health, auto saves, plenty checkpoints and straight corridors were all made for stoners :)