(FORTUNE Magazine) – This year more than $246 billion has moved into money market mutual funds, which invest primarily in short-term debt securities. While some investors are looking to park their assets until global markets stop wiggin' out, others are using theirs as a high-yield alternative to bank accounts. That makes sense because the average taxable money fund's annual yield is around 4.9%--about double that of any bank. Trying to capitalize on the boom, these funds have updated the banks' old toaster give-away promos for the '90s. Here are some of our favorites.

Best frequent-flier pitch: The Warburg Pincus WorldPerks Money Market fund sends its competition packing. Investors get one frequent-flier mile on Northwest Airlines for every $4 they invest. That beats most of the rest, which give investors one mile for every $10 invested annually.

Best substitute checking account: While some money market funds let you write only three to five checks a month, the U.S. Treasury Securities Cash fund, managed by U.S. Global Investors in San Antonio, offers unlimited check writing with a $1,000 minimum investment. The best part? Its 3.7% annual yield is much better than the corner bank's.

Highest yield: Oh, yeah, this is the reason that people buy money funds in the first place. The winner here is Strong Investors Money fund, which has an annual yield of around 5.6% and a $1,000 minimum investment.

--Julie Creswell