I specially registered to leave a comment for this plugin, because this really the best! You forget forever about the need to scale images, the need for watermarks, manualy choosing popups, and much more very useful pics ops. You can even choose separate autoresizing for blog format and showing full articles. You do not even need to have a separate gallery plugin, because BK-thumb can do that such as many other things.
"Must have" staff, no doubt. Very thanks for that!