Media analysis firm comScore yesterday released its 50 top-ranked Web sites for the month of February, showing that Yahoo is still the biggest destination, but the advertising power lies with AOL.

Yahoo continued its lead as the server of the most visited sites on the Web, with 137 million unique visitors in February. Yahoo was followed by Google with nearly 136 million, and Microsoft sites with over 118 million.

Though former comScore reports have shown thatYahoo delivered more display ads than any other ad network, the leading advertising network during the month was AOL and Advertising.com's Platform A.

The advertising network, which recently underwent a shift in its executive roster, reached a reported 90% of American Web users for the month, while AOL's site was also the fourth most frequented site in the rankings with just under 109 million unique visits.

These strong positions show AOL's evolution from ISP to advertising entity has been competently executed, and further acquisitions and development could facilitate even more growth.