Daily Planet (a discovery channel show here in Canada...don't know about anywhere else), just did an interview with a researcher from the Prarie Provinces where they were doing tests on rats with THC. They found that it increased activity in the hippocampus area of the brain up to 40% (that's the area for memory and stuff). So they think that cannabanoids found in marijuana could actually help with memory.
Check their website www.exn.ca/dailyplanet

Also, in my experience, anti-drug websites and such tend to be totally WRONG, misguided, bias and outdated. NEVER listen to them unless you've got a bunch of different sources, it's recent and doesn't come from the US government.
Almost ALL experiments using THC show that it's not harful, in fact its actually GOOD for you in many ways.

I was just reading the latest HEADS magazine (Ed Rosenthal Issue) and they have a little piece that says that a study done by dr donald tashkin (who used to say cannabis caused cancer) is now saying that it doesn't. In fact, there are no conclusive studies done TO DATE that can state that marijuana smoke directly causes lung cancer.

free the weed!