With 500k:
Half a million really isn't all that much money. At that level, you really can't afford to do anything risky. My strategy:
100k in each of two mutual funds: one that tracked the S&P 500, the other that invested in an industry you like. (Alternately, there are "socially conscious" funds--they don't do tobacco, they don't do defense, they don't do booze...one of those would be okay, if it performed well.)
100k buried in the back yard. Okay, buried in a bank somewhere. Put half in a money-market account, put the other half in regular passbook savings so you can get a new water heater without losing two months' interest.
100k in "tangible assets"--specifically precious metals. The American Eagle coins are nice, and they seem to perform well. You could spread this out a bit--put 20k in each of five different kinds of coin, which lets you take advantage of the rare-coin market as well as the precious-metals market.
100k in US Savings Bonds. Bonds aren't the highest-performing investment in the world, but on their redemption date you know they'll still be good.
With another 500k:
Double the investment in each of the aforementioned classes. You can get a bit more speculative with a million dollars, so looking at some higher-performance vehicles would be feasible. (Remember: upside comes with risk.)
At $5 million you can invest in a business or three and start employing people who need jobs. Remember: teach a man to fish, he eats for life; open a fish cannery, the whole town eats.
Okay, let's really play: With $10 million, I'm going to flight school, buying a Pilatus PC-12, and starting a business hauling shit around the Northwest for $1250 per hour.
This is a PC-12: