Google Scholar:
It's better to use it to search articles and patents. It seems that we can't search experts or something other by this. The first five result of "game theory" are cited by 1751, 2117, 2651, 978, 3601 times respectively, so I didn't think it rank papers or books in the number of it being cited.
Arnetminer:
It gives experts in one field, publications, conferences, journals and courses. But I see one paper appears twice..... And it doesn't surport you to change from expert to course or some others without typing in the query again.
For an expert, it gives his email and homepage, and a list of all the publications he participated in. It also gives a graph to show the relationship between him and other people, though some of them are wrong.
MS acadamic research:
It also output authors, publications, conferences and journals. It gives courses in publications.
For an expert, it gives a graph to show the number of his publications and the number of his citations. It gives not only the list of all his publications, but also the list of all the citations to his publications. It gives a graph to show all co-authors. What is interesing is that it gives a graph of "co-author path" to show his Erdos number.
