PayPal is aiming to launch an improved micropayments service by the end of this year. It hopes a bigger volume of tiny online purchases will be unleashed if buyers can pay as they go, instead of making a big upfront payment to be debited down.
Amazon has been one of the most resilient Internet stocks. But now, with the iPod, iTunes and iPad, Apple is seriously threatening Amazon's key strength -- its control over online sales of media. That's why the tumble in Amazon's stock could mark a turning point.