Ai Jesus. Is there no end to the devious techniques that Web marketers will use to track what people are up to? You may have heard about Comet Cursors before, maybe even downloaded them. The idea was hard to resist: customized mouse pointers that would change shape when you visited various Web sites. As it happens, though, the cute l'il cursors were watching what you were clicking on, and reporting the results back to the Web site's owner. (Weary sigh.)