One of the tools I use that mitigates the directory navigation delays is a Java class and package browser I wrote several years ago. The browser is a 300 line perl script that displays an interactive list of packages on the left and an interactive list of classes on the right. The significance of the class view is that it lists all the classes under a given package hierarchy and orders them by class name. For example, the figure shows all (4) classes under the "com.ingenta.oso" packages.

The tool is very simple but surprising useful. There is no comparison between it and powerful package and class browsing components in Eclipse and NetBeans. However, these weighty tools sometimes offer too much when all you want is a class file list and quick access to the source.