A free tool visualizing scientific research areas and trends through timeline graphs and bar charts, allowing users to locate other experts in a field of study and browse article results.
S. Doerfel, R. Jäschke, A. Hotho, and G. Stumme. Proceedings of the 4th ACM RecSys workshop on Recommender systems and the social web, page 9--16. New York, NY, USA, ACM, (2012)