Associated Bank's Preferred Platinum Money Market Account, which requires you also have an Associated Bank checking account, offers annual yields ranging from 0.40%--for balances below $10,000--up to 2.5% (as of May 2008)—for balances of $250,000 or more. The minimum opening deposit is $10,000. You must maintain an average monthly balance of $15,000 (for a standard Platinum account) or $10,000 (for a preferred account) to avoid fees. You get free ATM deposits and two free non-Associated ATM withdrawals each month (there's a $1.50 fee for additional withdrawals).