Setup an Adwords campaign say $0.25 CPC. Funnel the traffic to a page where you have Adsense ads paying $0.30 CPC. That's arbitrage for you. Not sure why you guys using gold and CDS as examples on HN.
You're forgetting something: click through rate. Unless it's somewhere above 90% (in which case you're one hell of a marketer -- or you're paying for the traffic), then you're essentially burning your money.