Data visualization is the study of the visual representation of data, meaning "information that has been abstracted in some schematic form, including attributes or variables for the units of information" (wikipedia).
Creately is a ‘diagramming’ tool, which can help you to wireframe an infographic before putting it into production. It includes a new real-time collaboration feature, allowing you to work on a design with a colleague or client simultaneously.
Tableau Public is a free service that lets anyone publish interactive data to the web. Once on the web, anyone can interact with the data, download it, or create their own visualizations of it. No programming skills are required. Be sure to look at the gallery to see some of the things people have been doing with it.
If you are in need of an infographic rather than a data visualisation, there is a new crop of tools out there to help. Visual.ly is probably the most popular of these. Although primarily an online marketplace for infographic designers, its Create option lets you pick a template, connect it to your Facebook or Twitter account and get some nice cartoon graphics back.
Voyant Tools is a web-based text reading and analysis environment. It is a scholarly project that is designed to facilitate reading and interpretive practices for digital humanities students and scholars as well as for the general public.