http://pedsexam.mc.duke.edu/MatrixB.htm PEDIATRIC DEVELOPMENT
http://www.blaufuss.org/ HEART SOUNDS
http://www.ecglibrary.com/ecghome.html ECGs
http://image-challenge.nejm.org/#10012009 Great place for Pics

Also my advice is: Try to look up stuff on internet, for example Hysterosalphingogram, or US of NTD, or X ray of SBO, CT of pulmonary fibrosis....and so on...Sticks to your brain better and helps with image challenge of the step