Transferring the My Clippings to your computer via USB is the quickest and easiest method. But, since all annotations from all documents are co-mingled, or if you make notes using more than one app or device, it may not be the best solution.
In those cases, I use this software: http://www.angelfire.com/ego2/idleloop/mbp_reader.html
It extracts the annotations from the book's .mbp file. It's a Windows-only thing, so I have to fire up Parallels to use it, but it's worth having around.
It can't extract notes from .tan files, so for annotations of Topaz files, you're limited to using the My Clippings method.