Who wants to be a millionaire?

John Catsimatidis, billionaire owner of Gristedes and Red Apple Group, NYC mayoral candidate
You’re always either selling yourself or selling a product. So you should find a product that you feel you can buy for less and sell for more. If I was down to my last $100, I would buy a case of apples for ten cents apiece and sell them for a quarter apiece. And soon I might have two or three hundred dollars. In a month, two or three thousand dollars.

Mary Buffett, ex-daughter-in-law of Warren Buffett, author of Warren Buffett and the Interpretation of Financial Statements
Vistaprint.com lets you print free business cards. You could invest $30 in cleaning supplies, and print business cards that say you’ll clean bathrooms for $10. I don’t know any business that wouldn’t have their bathrooms cleaned for $10. It’s not something you’d want to do, but it’s better than standing on the corner and begging. The oldest profession in the world will probably give you your best return, though. Just spend $50 on a fancy outfit.

Craig Zucker, founder of Tap’d New York (which bottles city tap water and resells it to a bottle-crazed public at local stores)
It’s hard to start a business on just $100. Not impossible, though, as good ideas always rise to the surface, no matter how little money is involved. Luckily, NYC is overflowing with great ideas. If I only had $100, I’d simply spend it walking around town talking with other New Yorkers, bribing them with food, drink, coffee and, in some cases, beers at a place like Old Town Bar. I actually do this every few months and have collected hundreds of great ideas.

Nick Schulman, Manhattan-based professional poker player
I would take 50 of it and try to run it up playing poker online at Full Tilt (fulltiltpoker.com) [where Schulman is a sponsored player], specifically 10¢ and 25¢ no-limit. I would take the other $50 and go to the pool hall, trying to make a few hundred to go play poker with. Or, if I was really disheveled, I’d just flip a coin for the hundred to get the ball rolling.

Make money»
Regular job not pulling in enough dough? Don’t have a regular job anymore? These easy side gigs will put much-needed extra cash in your too-empty pockets.