The Google Singleton Detector, or GSD, is a tool which analyzes Java bytecode and detects the use of Singletons. It's not quite as simple as that, however. First, GSD doesn't only detect singletons; it detects four different types of global state, including singletons, hingletons, mingletons, and fingletons. Second, it outputs a graph with all these different types of static state highlighted, and shows all the classes that are directly dependent on them. The point of this tool is to allow you to see all of the uses of global state inside a project, as well as how they are all interrelated.
The Maven-Grester plugin is a Maven2 plugin for Jester, the JUnit tester tool. It enables Jester to be executed at any valid Maven lifecycle phase in a Maven Project. It saves developers from constructing cumbersome Java classpath entries on the commandline every time they need Jester to run against JUnit Tests in the project. It can also help to dispense with a suite of scripts that may have been written to handle complex Java classpath executions for Maven projects.
LiquiBase is a DBMS-independent library for tracking, managing, and applying database changes. It is built on a simple premise: all database changes (structure and data) are stored in an XML-based descriptive manner and checked into source control. While there have been many attempts to provide a similar tool, LiquiBase aims to provide a solution that supports merging of changes from multiple developers, works well with code branches, supports a database refactoring IDE/plugin, and more.
Perl::Critic is an extensible framework for creating and applying coding standards to Perl source code. Essentially, it is a static source code analysis engine. It is distributed with a number of Perl::Critic::Policy modules that attempt to enforce various coding guidelines. Most Policy modules are based on Damian Conway's book Perl Best Practices. However, Perl::Critic is not limited to PBP, and will even support Policies that contradict Conway. You can enable, disable, and customize those Polices through the Perl::Critic interface. You can also create new Policy modules that suit your own tastes.
Structure101 is a tool to understand, measure, and control software structure. It allows you to see exactly how your high-level components depend on each other and why. You can use it to find out immediately when your architecture is accidentally changed by code-level changes at the coal-face. It can help you control structural complexity, since it can measure the complexity of methods, classes, and packages and warn you when given limits are exceeded. It can also discover the locations of productivity-killing package dependency cycles.