Every single business following the HYIP model has turned out to be a ponzi scam.
I would think that a "legitimate" HYIP would be possible however. Think of the real estate business. If you have a rental property as an investment, it is possible to make a 8-15 percent annual profit. A business could buy a property and sell shares in the property which would return a weekly, monthly, or yearly profit. Shares could be resold once bought, hence leaving your initial investment intact.
<...>
Got any other ideas?
That would not be a HYIP in the first place. HYIP is a type of Ponzi scheme, that is "an investment scam that promises unsustainably high return on investment by paying previous investors with the money invested by new investors" according to the Wikipedia article about it.
HYIP stands for high yield investment program. Any alternate definition written on the wikipedia page is merely the view of the latest wikipedia editor given historical data. I'm not saying that you're going to find a legitimate HYIP, just that re-defining an acronym is an incredibly stupid thing to do, especially considering its an acronym.