I read this book once about six years ago. It had a picture of an angry black cat on it, and the plot was centered around a summer camp at which unlucky things were happening. The main character was a female counselor at the camp. I distinctly remember something in the plot about a photograph with blood on it. If you can tell me what this is, I thank you.
Hmm...that sounds a lot like Lights Out by R.L. Stine (haha, I think I read every one of his books when I was in middle school). It's probably not, though.
Though judging by Stine's habit of rehashing plots it could be any number of his other books (is he still writing by the way?). Yes I to was an avid reader once. Feels embarrassed.
Noo, it was definitely not a Stine book, I liked him a lot back then. This was way more adult and risque than my twelve year old mind was used to at the time. I could look at this book anyway though.
I already thought of Stine's books and took a quick look. I didn't see anything like what you described. I tried some keyword searches as well, but wasn't able to narrow it down.