Let's make lots of money
Billionaires are known for being an eccentric lot. Of course, having more money than could possibly be spent in a lifetime probably has something to do with that. But for many of the world's billionaires, it was their wacky ideas that made them so rich in the first place.
It's worth keeping tabs on the ingenious concepts backed by the world's richest people, so here's our roundup. (Text: Bryan Nelson)