ETFs offer small investors access to a number of alternative investments to stocks. There are lots of bond/fixed income index ETFs available. You can also use ETFs to diversify out of US stocks (assuming you're a US investor) through international indexes. It is also possible to invest in other asset classes such as commodities and foreign currencies through ETFs but there are a number of caveats and potential hidden costs to many of these so you should do some research before going that route.