Coming soon to iOS, iCloud Keychain does two things you'll appreciate. One is that it can save credit card information entered on websites so you don't have to keep re-entering that data. (Relax: You still need to enter the CVV code, as iCloud Keychain intentionally does not retain that verification code.)
The other is that your saved passwords and credit cards are synced across your Macs and iOS devices if they're signed into the same iCloud account and have iCloud Keychain enabled. Apple has added extra verification to protect iCloud Keychain data, so another user would need more than your iCloud sign-in information to enable it. Use the Safari controls in the Settings app to manage the saved passwords and credit cards.