There is a ranking of journals by citation impact factor. I don't have a link to it though, and if anyone does I'd love to bookmark it.
Someone recently compiled a list of "journals of the century," including those listed below (
http://www.apa.org/monitor/nov01/journals.html). These are the "top top" journals in psych, cutting across all areas, but note that there are many great journals not on this list, including those with a more specific focus.
A good way to evaluate the impact of your POI's research is to go to PsychINFO and look at how often their work has been cited (of course, this won't work for their most recent work).
General
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American Journal of Psychology
American Psychologist
Behavioral and Brain Sciences
Psychological Bulletin
Psychological Methods
Psychological Review
Psychological Science
Applied Psychological Methods --------------------------------------------------------------------------------
Journal of Applied Psychology
Journal of Counseling Psychology
Organizational Behavior and Human Decision Processes
Personnel Psychology
Biological/Physiological
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Behavioral Neuroscience
Journal of Comparative Psychology
Psychophysiology
Clinical/Abnormal
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Journal of Abnormal Psychology
Journal of Consulting and Clinical Psychology
Developmental
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Child Development
Developmental Psychology
Experimental
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Cognition
Cognitive Psychology
Journal of Experimental Psychology (includes all five individual sections)
Journal of Memory and Language
Perception & Psychophysics
Mathematical
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Psychometrika
Personality/Social
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Journal of Experimental Social Psychology
Journal of Personality
Journal of Personality and Social Psychology
Personality and Social Psychology Bulletin