We are pleased to announce the finalists in MediaPost's first-ever OMMA Awards for online advertising creativity. Winners in 19 categories will be selected from the finalists you see here and honored at a special OMMA Awards reception on Sept. 26, 2006 at 6 p.m. at the New York Marriott Marquis in Times Square. In addition to celebrating the category winners, we'll be awarding Best in Show and Creative Breakthrough of the Year to those agencies that have produced the best work of the year. In devising the awards categories, we strived to take into account …