  April the first Google mail provides one gigabyte of storage - many times more than existing rivals that also offer free e-mail. Each user would have storage equivalent to 500,000 pages of e-mail, said Google. ' urlLink 'But there's a catch to the new service. Hoping to turn a profit from Gmail, privately held Google has programmed its computers to dissect the topics being discussed in the e-mails and then deliver text-based ads related to the subjects. For instance, an e-mail from one friend to another discussing an upcoming concert might prompt Google to include an advertising link from a ticketing agency. ' 
