A general purpose source code indexer and cross-referencer that provides web-based browsing of source code with links to the definition and usage of any identifier. Supports multiple languages. Up-to-date information in http://lxr.sourceforge.net
A very powerful java bytecode viewer and decompiler which makes use of the javassist open source library.
A query language for code browsing. You query your database-- why don't you query your code? Write queries to provide custom views of your Java or C#/CLR code base. Integrates with popular IDEs or standalone.
State Machine Diagram Plug-In for Eclipse/CDT
Provides an Eclipse Plug-In to display state machine diagrams from C/C++ code.