I also think it's pretty clear that Pamela was the cause of Jim's death--she gave him some of her heroin (I think she told him that it was cocaine) and she was too stoned during the night Jim was dying to do anything for him. Albeit, I don't think she did it purposely--everybody says she felt insanely guilty after Jim died.
By the way, am I the only person who doesn't find Pamela very attractive? I guess she's got the red hair, if you like that, but otherwise, I think she was average-looking. That's not to say that you should judge someone soley on their looks (but it doesn't seem like she was that nice a girl, anyway) but I keep reading stuff online about people finding her so beautiful and I don't really see it. I don't think anyone could ever be as beautiful as Jim, of course, but I definitely don't think Jim kept her around because of her looks. Pam's mother said in The Doors book that Pamela "looked like she had stepped off the cover of Vogue." Um, I'm sorry, but no, she doesn't. Pamela was cute, but not beautiful.