There are many, many organisations dedicated to this cause, the Nimbin HEMP Embassy, and NORML are my two favourites.
The Nimbin HEMP Embassy, (phone; Australia-02-66891842) is home to the Help End Marijuana Prohibition political party, they have libraries of information on cannabis, cannabis use, and they keep trying to get somebody elected that see's things clearly.
NORML,National Organisation for the Reform of Marijuana Laws, what can I say, it's been around forever. Get 5 smokers together, join NORML, and you can form your very own NORML Chapter. The Kiwi's have it organised, come on Aussie bong on, bong on...
Are you happy with the way things are? Otherwise law abiding citizens persecuted solely because they get high. Do something, even if you change the way just one hypocrite thinks, you'll have done plenty...