Looking for some free online tutorials? Google under its Google Code for Educators is offering teaching material aimed at CS educators aiming to strengthen their courses with some of the latest computing technologies and models. In the tutorials section one comes across various online tutorials which offer a refresher course on latest technologies. In the sample course content section one can access teaching material in the form of readings, lecture slides, projects and problem sets which can be downloaded.

Since the material is available under the Creative Commons license it can be modified and used freely as per the license agreement. In the video lecture section one can access videos of lectures of the related areas and even search for published teaching material from CS departments worldwide. Here you can access tutorials with respect to Ajax programming, web security and distributed systems which look good to me. Check it out here.