From Benjamin Wiederkehr, Editor of Datavisualization.ch, a more comprehensive list of exceptional data artists may not exist anywhere:
Nicholas Felton http://feltron.com
Stefanie Posavec http://itsbeenreal.co.uk
Always With Honor http://alwayswithhonor.com
Column Five Media http://columnfivemedia.com
Golden Section Graphics http://golden-section-graphics.com
Catalogtree http://catalogtree.net
Hyperakt http://hyperakt.com
David McCandless http://informationisbeautiful.net
Tiffany Farrant http://tiffanyfarrant.co.uk/