THANOSD  Excellent work in the public domain. This is the kind of tool you NEED when you are in image processing and want to analyze a new type of image. This saves time and resources, since it provides all functionality I would usually find in either expensive image processing suites or environments, such as Matlab. Congrats to the developers!  
(Version 1.4d)

TOMIS  I found it to be extremely buggy. It wasn't able to access an image on the clipboard at all when no other Mac app had a problem with the clipboard image.

Then when opening a JPEG of aprox. 2500x1900 it threw an out of memory error, which is an absolute joke on a 768MB system that had 160MB free at the time. Considering Preview.app opened the same image flawlessly, what gives?

I would give it thumbs down. Maybe wait until they do a Cocoa/Java port? Who knows. It just doesn't feel very polished at this point.  
(Version 1.3.7m)

ANONYMOUS  Thanks for this Java program. It's easy to use and it's fast.  
(Version 1.33p)

IN LALA LAND  Madena is much better. More controls, better interface, faster and the same price (Free).

Still ImageJ might have its uses (primarilly if you are operating on a cross plaform basis). Either provide control and manipulation of 16-bit level data in either TIFF or DICOM files. Something GIMP can NOT do.  
(Version 1.32i)