What services that I can't use when I unsubscribe the mobile me?
According to the Terms of Service (number 10) you will not be able to use any of the services you are currently paying for after termination of subscription.


  Upon termination of your account you lose all access to the Service and any portions thereof, including, but not limited to, your Member Account (any Sub-accounts thereunder), Subscriber ID, email account, iDisk, domains, iChat account and MobileMe Gallery albums.