Smooth Metal look & feel:SmoothMetal is a wrapper for some of Sun's Java Look and Feels to enable anti-aliasing.
Anti-aliasing is the process of smoothing text and images by introducing intermediary colours to fool the eye into believing that the resolution is somewhat higher than it is. Thus a black character on a white background is 'smoothed' with shades of grey. You can see this in Windows XP when using ClearType, or enable it in X11 using Xft. MacOS X and RISCOS users get it for free along with KDE and Gnome desktop users on Linux, Solaris and elsewhere.
While operating systems have moved ahead and most now offer anti-aliasing, Sun has said it will not be officially offering anti-aliasing in Swing until Java 1.5. SmoothMetal allows you to get around this and make your Swing apps look just a bit better.
Liquid look & feel:The goal of this project is to provide a look and feel based on the Mosfet Liquid KDE 3.x theme.
Office 2003 & XP look & feel:This project provides a single jar file that you can add to your Java Swing applications to enable Look and Feels modeling the following popular Microsoft applications:
Office XP
Office 2003
Visual Studio 2005
Of course, your Swing application MUST be running on a Windows box to use these LnFs. The reasons for this are twofold: first, the LnFs are built upon the standard Windows Look and Feel, which is available only in Windows JRE's, and second, I'm not too sure about the legal ramifications of copying Windows applications' look and feels/icons/etc. on other platforms.