Big publishers are facing an unexpected legal headache. Over the past two months, a little-known entity called Rich Media Club LLC has filed lawsuits against major news publishers, accusing them of using online ad tools that it says infringe its patents.The publishers targeted include Comcast, Guardian Media Group, Gannett, News Corp's UK publishing arm News Group Newspapers, and MediaNews Group, which publishes dozens of local newspapers. The legal action comes at a challenging time for web publishers, w ...