Twitter is a service for friends, family, and co–workers to communicate and stay connected through the exchange of quick, frequent answers to one simple question: What are you doing?.. 

http://twitter.com/

TwitPic lets you share photos on Twitter. You can post pictures to TwitPic from your phone, our API, or through the site itself... 

http://twitpic.com/

Offers to tweet the last posts published in a blog via the RSS feed. Twitterfeed can post directly to twitter, identi.ca, custom laconica installations, and via HelloTxt or Ping.fm, simultaneously to the many platforms supported by these services... 

http://twitterfeed.com/