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.