If you’re published, or about-to-be published, you’ve heard plenty about establishing your online presence with a website and/or blog and various social networking sites you can use to spread your message and promote your book. Twitter , probably the most popular and the most ridiculed of all social sites, is popular with readers and writers. Even more exciting, agents and publishers hang out on Twitter . This venue offers several features that can be useful to writers. The one I’m looking at today is Lists. The List feature appeared in 2009, but I ignored it at first. It seemed like one more way to waste time. Now that my follows total about 850, I realize how convenient it is to have a few specialized lists that allow me to see a stream of messages from a few selected people. Since I’m about to embark on an agent search for my new novel, I want a convenient way to scan agent comments and advice before I send queries. To accomplish that, I created a new list called “Literary Age...