CAPTCHAs are like speed bumps; a mild frustration that all of us must endure to thwart the few sociopaths hidden in our midst. But now a new spin, called reCAPTCHA lets you block spambots and help digitise archived manuscripts at the same time.

The idea is that they let the OCR program scan the document first and then all the words that the OCR can't match get thrown into a pot to be used as images for CAPTCHAs on any web site that signs up to the service. When a few humans have agreed on what the word says, that gets fed back to the archiving people and another word is crossed off the list. One hundred million CAPTCHAs processed every day means enough typos to fill a thousand novels could be corrected every day.

It sounds like it's a great way to harness untapped processing power and let us all feel like we are doing something useful every time we register on a new website. But actually, of course, it is just another micro-payment stealth tax. That's not necessarily a bad thing, but let's call a spade a spade. Here are my suggestions for other resources we could exploit:

  • Micro-generators implanted in the fillings of your teeth that charge your cell phone as you chew.
  • A system of air ducts to divert waste heat from CPU heat sinks to warm the swimming pools for the London Olympics.
  • New tropical rainforest zone in World of Warcraft full of real plants, with quests that reward players for identifying cancer-curing drugs.
  • Community composting scheme for spam that allows junk emails to be recycled into great works of literature about heroes with greatly enlarged penises and impressive stock portfolios.