Twitter’s #hashtag: Handy search device, or irksome clutter? Tool is used to mark tweets about anything from #Aardvark to #zoology. By Ragan StaffMay 20, 2009 SHARE To read the full story, log in. Become a Ragan Insider member to read this article and all other archived content. Sign up today Already a member? Log in here. Learn more about Ragan Insider.