########## Preferred ##########
Weblaf: Very nice suite with modern and minimalist interface. Fewer dependent packages. There are open source and commercial agreements.
Https://github.com/mgarin/weblaf
Pgslookandfeel: Simple and modern interface, Apache2 Open Source protocol
http://www.pagosoft.com/projects/pgslookandfeel/
Seaglass: Pretty UI, Modern interface, is based on Java 7 with skin Nimbus improvements
Https://github.com/khuxtable/seaglass/wiki
Synthetica: Very nice suite, modern interface, each skin file is very small, only about 200K. Half of the skins are free, but some of them are more aesthetically pleasing in need of commercial authorization
http://www.javasoft.de/synthetica/themes/
########## selected ##########
Beautyeye: UI developed by the Chinese, modern interface
Https://github.com/JackJiang2011/beautyeye
Jtattoo: Sub-gpl/lgpl/apache three kinds of agreements, there are open source and commercial version, personal preferred the Luna style
http://www.jtattoo.net/
Insubstantial:substance Project's Branch project
Https://github.com/Insubstantial/insubstantial
Nimbus:java SE 6 Update 10 after Oracle built-in skin, if you want to be safe and stable, choose it right
Http://docs.oracle.com/javase/tutorial/uiswing/lookandfeel/nimbus.html
########## other ##########
Quaqua: The whole Mac OS-like interface
Http://www.randelshofer.ch/quaqua/index.html
Alloy: Commercial, feeling in general
http://lookandfeel.incors.com/
Jgoodies: Commercial, feel more general
http://www.jgoodies.com/products/swing-suite/
Java Swing Skin (look and feel) Daquan