I recently obtained a membership to the National Center for Case Study Teaching in Science (NCCSTS). It was not as easy as you would expect. The company is extremely strict about handing out teacher notes and answer keys. You must prove you work at a school with an email found on your school webpage, or alternatively, a letter on school letterhead indicating your employment.
I found this site over a year ago, but did not actually gain access until recently. I was in love the first time I found it. The case studies are intriguing, engaging, and cross-curricular. The database currently has 711 case studies in all areas of science, appropriate for different age groups. In my case, I have been looking for case studies for Biology and Anatomy and Physiology. You can search by subject heading, educational level, type/method of instruction (discussion, debate, experiment, journal, analysis, etc.), topical area, or even by date.
The mission of the National Center for Case Study Teaching in Science (NCCSTS) is to promote the nationwide application of active learning techniques to the teaching of science, with a particular emphasis on case studies and problem-based learning. (http://sciencecases.lib.buffalo.edu/cs/)
This type of active learning resources fits in well with the NGSS standards and current learning goals for the students.