Online ad revenue is up at The New York Times Co., but not enough to compensate for lost print revenue, the company reported Thursday. Third-quarter online revenue grew to $62.8 million, up from $50.5 million from last year. Web businesses--including About.com, digital archive, NYTimes.com and Boston.com--now account for 8.5% of overall revenue, up from 6.7% one year ago. At About.com, third-quarter revenue increased 29.3% to $18.3 million from $14.2 million, which the company attributed to ad and e-commerce revenue. Operating profit increased to $6.4 million from $3.8 million. But total revenue at the company slid 2.4% to $739.6 million from $757.8 million. Ad revenue company-wide decreased 4.2%, with an even further slide--5.1%--at The New York Times Media Group and the New England Media Group. The subscriber-only premium service, TimesSelect, now has 551,000 subscribers, but about two-thirds--65%--receive the service because they have home delivery.