If you want to keep the same iTunes account so that you can share apps, music, books, etc; then what you want to do is to keep them on the same iTunes account, but give them new Apple ID's for an iCloud account. They can be different. Here's Apple's support page on the subject.
Apple IDs and iCloud
You need to be running iOS 5 or later to do this, and should be able to set those accounts up under Settings > iCloud.
Or if you are on iOS 4.x and don't want to upgrade the iPads you could give them GMail, Yahoo, or some other free online email service. Set those up online then add the accounts under Settings > Mail, Contacts, Calendars > Add Account. To get contacts with a GMail account you will have to set it up as an Exchange account.
Setting up Google Sync with your iOS device - Google Mobile Help
I recommend iOS 5 and the iCloud account; for two reasons. One, it's best to upgrade now when you don't have a lot of stuff on the iPads.That way if it goes wrong you have less to add again (don't worry, it shouldn't cost anything). Second, you won't find better integration for the built in apps than Apple's own service. If you're not already invested in using another service you might as well get those benefits.
And, you can always add other services later if you need them. The iPad handles multiple accounts easily.
