Tonic Look and Feel
This pluggable look and feel is a substitute for the default native look and feel of Swing, 'Metal'. Metal lacks both in usability and aesthetics. It contains considerable graphical noise, distracting the user from the key elements of the GUI.
Tonic, on the other hand, tries to provide a clean, balanced look and an improved feel. Tonic is available free of charge for non-commercial applications, and can be used for a small fee in commercial applications as well. It lends a professional touch and a very tidy and clean interface to your Swing based applications.