MailTones is an app for your iPhone that lets you associate email from different people with different tones.
Setup is easy if you already have a Gmail account. If not, set one up so that the forwarding fun can begin, as you have to have your email forwarded to the MailTones server in order to work. You really don’t need Gmail, but I suggest it because you can have all of your email accounts in one location, and then setup the forwarding from there.
I enjoyed the concept, but there is a slight learning curve in remembering which tone belongs to who! But once you get that down you can enjoy your email. Now instead of the plain ding you would normally hear you can be made aware of important email without constantly checking your phone.