Just wanted to add my toughts on this thread.
I smoked resin from about the age of 14 up until the age of around 17/18 when I started smoking skunk.
Before I went to Uni, I only really smoked marijuana on the weekends, or on school holidays. Yhat moderation meant that I wasn't abusing the drug and I found that it was causing very little, if not any damage to my health or physcological behaviour at all.
However, when i started Uni last year, Skunk was easily available and I would spend around £40 ($65) on weed. I'd have alot of free time on my hands at Uni so I'd usually just sit around watching tv, getting stoned all day. I started having reversed sleeping patterns, staying up until around six in the morning, going to ebd and then getting up at around 5pm.
I never missed any lectures, but I could never concentrate and my health went downhill pretty fast.
It wasn't all the weed's fault, but I ended up quitting Uni after the first year, but it definately had a part to play.
Despite this, I am a strong believer that Cannabis should be legalised outright. It is a pleasant and social drug which could be substituted for alcohol with less dangerous effects.
I was using marijuana at Uni like a drunk would abuse alcohol.
USE IN MODERATION!
However, marijuana is relatively safe drug and if used properly can not only be pleasant but healthy.
Doctors and scientists know that cannabis should have been the next penacillin, but it remains illegal for numerous stupid laws.
I hear you guys get it bad over in the states, with really awful anti-marijuana propaganda adverts. The majority of these sound like rubbish.
Read-up about the herb. Educate yourself. Don't be influenced by others. Especially people who don't have a clue about it.