If you have multiple email accounts set up on your iOS 6 or iOS 7 device, you can have each one play a different sound when new messages arrive. That way, you could instantly know whether an email is work-related or whether you can safely ignore it. Sweet!
You'll start configuring things by visiting Settings> Notifications> Mail in iOS 6, or Settings> Notification Center> Mail in iOS 7.
Then within those preferences, you'll select each of your accounts in turn to set up their sounds.
Under each account is a setting labeled "New Mail Sound," which is what you'll change.
Pick from the list of your available tones within, and that's all there is to it! Afterward, repeat for your other accounts, and you'll instantly know where your new emails are arriving. This is especially useful if you're like me—I've got approximately 80 email accounts, but only a couple of them receive anything other than ads for enlarging…things.
Note, too, that you can set up plenty of other account-specific preferences while you're in there, like whether each particular account adds to the numbers on your Badge App Icon, which accounts show previews of new messages, and so on. So you can tailor each one to your individual needs for privacy and whatnot. And one final caveat: If you can't get those sound changes to take effect in iOS 6, try rebooting your device. For some reason, there's a bug for a few folks where the settings won't apply without a restart. Weird, huh?
So, guys, this'll probably be my last iOS 6–specific tip. I'd like to thank the Academy, and my cat for always believing in me, and that motivational t-shirt I saw that one time. iOS 7, here we come!