According to comScore Media Metrix April monthly report, the notable trends during April were the marked increases in traffic to real estate sites, which grew 12% from the previous month and 23% in the past year.

Another noteworthy trend borne out online in April was Americans’ intense interest in tracking ever-rising gas prices.

Yahoo! Sites retained the number one spot in the U.S. with 128 million visitors, while MSN-Microsoft Sites regained its number two position, attracting more than 120 million visitors. On a worldwide basis, MSN-Microsoft Sites ranked highest in unique visitors in March, followed by Google and Yahoo! Sites, according to comScore’s World Metrix.

Top 50 Ad Focus Ranking: Advertising.com extended its reach to more than 83% of Americans online and retained the number one position for the 24th consecutive month. WebMD Health Network moved up five spots to number 30, reaching more than 5 million more Americans in April than in March. Tremor Network entered the Ad Focus ranking for the first time at number 15, reaching 40% of the U.S. population online.