Is there an app available to customize notification sounds? I know that you are given choices for ringtones and SMS's, but I'd like to use a different sound for "new mail" than the one I'm presently stuck with. Wife also has an iPhone so it's impossible to know who's phone has just beeped. I really don't want to get the thing jailbroken, which is what all the Google searches tell me I need to do. Thanks.