By Mike Fruchter of MichaelFruchter.com (Twitter/FriendFeed)There are hundreds of Twitter applications on the market, many of which have been covered previously on this blog, including a number of clients, such as TweetDeck and Posty. With the Twitter ecosystem continuing to grow, as evidenced by last night's post on SocialToo, I wanted to touch upon a few that I use, and that I feel are unique and useful. This post highlights fifteen different Twitter tools that I believe would be excellent additions for your Twitter toolbox.1) TwufferTwuffer is a simple, useful utility that allows you to schedule pre-written messages for posting... [Tags: backlog, calendar applications, calender, csv file, date time]