All forms of money other than those in M1 are referred to as near money because, although readily available, they must be converted into checkable deposits before they can be used. Up to now credit cards have not been considered as money because the use of a credit card is assumed to be conditional on a loan by the issuer. Reserves of banks are not part of money because that would be double counting.
With high interest rates of the 1980's, several new forms of financial instruments have emerged. Mutual funds offered money market accounts with return much higher than normal bank certificates of deposit. Recent decreases in inflation and interest rates took away some of the appeal of money market account. Still, they are a good alternative to holding money in a checking account.