And as well as the book mentioned in the last post, there are the various books by John Hampton:
ECG made easy
150 ECG cases
ECG in practice
Look for them in your library!
Nathanson LA, McClennen S, Safran C, Goldberger AL. ECG Wave-Maven: Self-Assessment Program for Students and Clinicians. http://ecg.bidmc.harvard.edu.
You can browse a case list, with or without diagnoses, or see a random case, and you can search for particular diagnoses. If you like it on Facebook, you get notifications of new cases.
Here are some other sites about ECG interpretation. Some I mentioned last time, some not.
ECG Learning Center, University of Utah
Life in the Fast Lane, ECG Library
Analysis and interpretation of the electrocardiogram, Queen's University School of Medicine (Kingston, Ontario)
ECG (EKG) interpretation, Oxford Medical Education (read this to find out more about them - not part of Oxford University or OUP).