Tonic Look & Feel
Un look & Feel java assez agréable et faisant penser à certains themes GNOME :
This pluggable look and feel is a free substitute for the default native look and feel of Swing, ‘Metal’, distributed under the GNU Lesser General Public License. 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.
[Update] Un autre, un peu plus fantaisiste : Napkin Look & Feel.