Earlier this year, executives at Dell Inc. tried to shut down DellComputersSuck.com, a Web site promoting an obscure brand of computers. Dell's lawyers dispatched a stern letter, and within a few days, the site's owner revamped it into an online discussion group about computers. The old version disappeared from view. The PC giant still wanted to seize the address, a move permitted under rules governing the use of domain names. But Dell had to prove to an arbitration panel it had been used in "bad faith." So Dell's legal team turned to the Wayback Machine, a massive archive of Web...