Imaging expert and award-winning author Deke McClelland presents his list of the top 40 features in Photoshop
—beginning with #40 and working his way up to #1—one weekly video at a time. They're almost done with the 40, so you can start watching the first ones and by the time you're done - they have posted the last few.
Deke goes over the function (i.e., eyedropper, layer comps) and explains why it is important and then shows some tips on how it can be used. I think the videos are useful for newbies and more experienced users. They are part of the Lynda.com Lyndapodcasts Channel which has other videos of use to many of us. And they are free !!