Display advertising is a large part of the revenues at major e-mail sites; nevertheless, it apparently is becoming a smaller part.

According to Nielsen//NetRatings AdRelevance, e-mail sites garnered just 44.2% of banner ads in December 2006, down from November’s 47.5% and October’s 51.1%.

Of course, it should be noted that display advertising fell slightly overall in December. Online advertisers ran 257.7 billion display ads last month, compared to 259.6 billion in November.

The top five advertiser categories for display ads for December was led by financial services, accounting for 29% of online display ads, up from 25% in November. Web media was the second-largest category, with 17% of impressions, though down from 20% in November. Retail goods and services accounted for 16% of impressions, flat from November; telecoms accounted for 13%, up from 10% in November; and public services held the fifth spot with 6%, down from 9% in November.

Nielsen//NetRatings also reported that, as usual, Google was the top search provider in November, as ranked by total searches, followed, by quite a ways, by Yahoo! and MSN.

Nielsen//NetRatings estimated that 3.1 billion search queries were conducted on Google, representing some 50% of all search queries conducted during the month.

According to comScore Networks, in December the story was much the same, with Google sites capturing 47.3% of the US search market, a slight .4% gain over November. Yahoo! grew .3%, maintaining its second-place ranking with 28.5% of US searches, and MSN was third at 10.5% of searches.

By comScore’s calculations, Americans conducted 6.7 billion searches in December, up 1% over November.

Via eMarketer