Photoshop Trimming – Delete All Empty Layers
Most of the time working with Silverlight or Flash you will be given a design for an entire site but you only want to work on part of it. So you want to get rid of everything that doesn’t relate to what you’re working on.
Cropping and trimming unfortunately still leaves loads of empty layers which makes it hard to find the layers you need to work on. So you need a script that deletes all the now empty layers leaving you with the good stuff. Wahoo! Some kind sole has written one
Tim Neil's Blog 