Sorry you're bored all the time. That can't be any fun. ):

I like scatterbrained's ideas of working on improving your skills. It helps keep you a desirable employee and keeps you mentally sharp. You'll probably feel a lot better doing something like that since you'll be distracting yourself as opposed to being alone with your own thoughts.

But you should talk to your manager before she finds out. It'll look bad on you if you don't speak up... because if she finds out, she may think you're irresponsible and untrustworthy. You don't want that. Plus, if you tell her you want to do more work, she may think very highly of you.