I found this really interesting clip on YouTube regarding the not so obvious medical benefits of marijuana, check it out! It's taken from a PBS documentary. At the 6 minute mark they talk about its effects on memory and the possibility of honing it to treat PTSD -- really interesting stuff!
http://www.youtube.com/watch?v=2sx6AQQpjPo
http://www.youtube.com/watch?v=2sx6AQQpjPo