jLogMan displays the current state of java.util.logging's Loggers and Handlers in an "Outline" (a tree table widget). With it you can create new Loggers and Handlers and change logging levels. There are Actions to save/restore logging configurations to/from files and an option to apply the configuration at startup. It can be dropped into any swing app (tested with jre 1.6 and 1.7); there is a NetBeans plugin. See the wiki for details and docs.
VisualVM - All-in-One Java Troubleshooting Tool. VisualVM is a visual tool integrating several commandline JDK tools and lightweight profiling capabilities. Designed for both production and development time use, it further enhances the capability of monitoring and performance analysis for the Java SE platform.