Start of an ATM program
The main thing I would say here is that you have 2 nigh identical functions apart from the balance being passed to them. Instead of checking_account and savings_account being different functions, make a single account_interaction function that takes an argument which you can then pass to the choden function.

def account_interaction(account):
    print "You have $%i available" % (account)
    print """
    What would you like to do:
    [W]ithdrawl
    [D]eposit
    [T]ransfer funds
    """
    choice = raw_input("&gt; ")
    if choice == "W":
        withdraw_funds(account)
    elif choice == "D":
        deposit_funds(account)
    elif choice == "T":
        transfer_funds(account)
    else:
        print "Invalid input.."


Ideally account would be a class, or at least a dictionary that contains multiple relevant values (ie. type, amount, account holder), either of these makes it easier to pass them around functions like this.