Mark Pilgrim made a cute (and simultaneously ugly) illustration explaining Web Workers, a neat bit of Javascript magic that runs in parallel to the main page. It’s a clever, cool and very capable piece of technology that was sorely missing all these years.
Here’s the thing about using comics and illustrations to explain things: they tend to over-simplify the most complex things, as Mr Pilgrim has done. Wikipedia has an example using a Web Worker thread to continuously compute prime numbers – yes, prime numbers. HTML5 Web Workers are only for those who know what they’re doing.
For the rest of us… hey, what else could go wrong?