Wired News describes the Web measurement market. Both Nielsen/NetRatings and comScore employ panels of web surfers – in Nielsen’s case, about 37,000 people; comScore, 1.5 million – who allow the companies to install monitoring software on their computers to track the websites they visit. There are also incentives: Nielsen promises $50 a year to home users ($100 if you consent to do it at work), while comScore offers free virus protection, an internet accelerator program to speed up dialup connections, and even sweepstakes prizes.