Is the drop in internet advertising getting worse?

In January several large internet companies reported that their online display ad CPMs were off 20 percent or more from the same month a year ago. Now it is beginning to look like that drop has accelerated to 30 or 40 percent in February -- and March is not looking better.

The most ominous sign of falling ad rates: the number of advertisers who only pay rock bottom for ads is getting larger. Ads from companies that used to pay premium rates, especially cars and financial services firms, have almost disappeared.