Some television networks are beating their estimates for online ad sales and are scrambling to sell more inventory, TVWeek.com reports
. Networks including ABC have reached the number of viewer impressions they promised advertisers and have been running promotional spots until new sales are made. NBC said it has beat its online sales estimates. That demand for online spots has surged, and the TV ad market stays tight, Web advertising prices are rising, TVWeek says. Generally, Web spots sold on network shows command $30 per thousand viewers, while networks get about $25 per thousand viewers.