SermonSearch.com and BibleStudyTools.com are both rich resources for finding sermon outlines online, as of May 2015. Most of the websites are free for pastors; however SermonSearch.com offers new members a 30-day free trial before a paid membership.
Other websites that features sermons and sermon outlines for pastors include PastorsHelper.com and SermonSeeds.com. Sermon Seeds has many outlines organized by Bible chapters. It also offers topical sermons and special sermons, such as sermons for communions, funerals and other events. Holidays are also included on this site, with holiday sermon topics for Christmas, Easter, Father's Day, Mother's Day and Palm Sunday, among others.