English-Finnish Psychology Dictionary
Extremely useful website for checking psychological vocabulary

List of psychological theories
A Wikipedia page. You don't need to know all the theories in psychology, there are a lot of them, but this wikipedia page can help you to understand something about the scope of psychology.

How theories are used in psychology?
A summary of theories in general and the nature of theories in psychology

Psychology wizard
This is not an IB Psychology site, but contains some good info on psychology 

25 famous psychological studies
Summary of famous psychological studies