The day before google went IPO and created new millionares, they brought in John Bogle to advise them to stay away from mutual funds or whatever and at the riskiest, stick to index funds if they were comfortable with risk and then just put the rest into stable investments if they weren't.
An interesting piece of advice I got from my finance professor way back when: Put your money into either index funds (or the more liquid, cheap to get out of Index Future) or treasuries. If you are risk adverse, do more treasuries, if you are more risk taking do more funds (or if you really want to take on risk, lever up). But always stick with these assets, as they are much more reliable than mutual funds or the ilk.
Not sure what he'd say now. US treasuries arent the sure bet they were 5 years ago and who wants to put any money into the movement of the S&P? There is something attractive to me in having a few gold bars in a Swiss lock box, though.