Josh Groban & Solange are among 2013's top tweeters

Josh Groban, Solange Knowles, Samuel L. Jackson and Mia Farrow have been named among the 140 top Twitter.com users of the year (13).

Editors at Time magazine have singled out their favorite micro-bloggers in honor of the social networking site's seventh anniversary this month (Mar13).

Jackson, Groban and Solange were all noted in the Celebrity category, alongside hip-hop producer/drummer Questlove of The Roots and actresses Anna Kendrick, Rashida Jones and Girls creator and star Lena Dunham.

Farrow earned a mention in the Activists group for her constant online campaigning for human rights, while supermodels Tyra Banks, Kate Upton and Coco Rocha were listed in the Fashion and Beauty category, next to designers Michael Kors and Nicole Richie.

Others to make the top 140, a reference to the 140 characters users are allowed in each post, include tennis star Serena Williams, Microsoft founder Bill Gates and former First Daughter Chelsea Clinton.