FLITE has a number of choices for those times when Wikipedia just won't cut it as you learn more about your topic.
Calsidyrose. (2010). Compass Study [photo]. CC. Retrieved from http://www.flickr.com/photos/calsidyrose/4925267732/
You can look in CREDO Reference, which covers a little bit of everything (including psychology).
Or, you can check FLITE's catalog for psychology encyclopedias. Some are in print, but others are online!
From The Mental Elf (shortlisted for the UK Science Blog Prize 2012)