Commercial
Borland JBuilder, IBM VisualAge, IntelliJ IDEA, Microsoft Visual J++, AnyJ, Cirquet Solution Suite, Cocktail, Compuware OptimalJ, ElegantJ, eVisNet Spirit(TM) visualJava tool, Fulcrum, inteRAD build-IT, Metrowerks CodeWarrior with Java, NCStudio
Open Source
Eclipse, Amy, Ginipad, Gwydion Sheets, jEdit, NetBeans, Red Hat Source-Navigator, Schmortopf, Sun Labs Jackpot
JavaWorld Developer Tools Guide: IDE
A pretty long list of java IDE's + descriptions
SunOne Studio
For Windows 95/NT, MacOS, Solaris, OS/2, and any other Java-enabled platform. Based on Netbeans. [Commercial and freeware editions]
Technical Stuff - Selecting a Java IDE
A guide to selecting a Java Integrated Development Environment.
The Java IDE
A Java IDE includes code editing highlight, code completion, debug and compile capabilities. Also built-in API help, framework code generator. [Shareware]
Vibe-Yet another IDE (VIBE)
An IDE that enables to automate the design and development of infrastructure components for complex distributed cross-platform, cross-language systems applications for DB, XML rendering, EJB 1.1 and Infor Bus like IBM MQ. [Free and commercial versions]
Visual Paradigm IDE for Java
A Java IDE includes code editing highlight, code completion, debug and compile capabilities. [Shareware, 180 days]
WebIDE
An experimental online development interface for compiling Java applets and applications. The current version offers editing, compiling, syntax highlighting and searching for help.