Transformation Tools

Tom - A Pattern matching transformation system.
http://tom.loria.fr/

Cross Module Inliner - CMI is an optimizing frontend for gcc which allows gcc to inline across module boundaries without requiring you to put inline functions in header files or even mark inline functions for inlining.
http://www.cs.utah.edu/flux/alchemy/cmi.html

Stratego (Strategies for Program Transformation) - A modular language for the specificat ion of fully automatic program transformation systems based on the paradigm of rewriting strategies. Free software.
http://www.stratego-language.org/

DMS Software Reengineering Toolkit - Generalized compiler technology for custom parsing, analyzing, transforming, and prettyprinting computer languages, including C, C++, COBOL, Ada, Java, C#, SQL. Tasks range from metrics to migrations. [Commercial]
http://www.semanticdesigns.com/Products/DMS/DMSToolkit.html

Trimaran - An "integrated compilation and performance monitoring infrastructure", facilitating compiler-optimization research and involves a collaborative effort by Hewlett Packard, University of Illinois and New York University.
http://www.trimaran.org/

Spoon: Program Processing, Analysis, and Transformation in Java - Spoon is a Java program processor that fully supports Java 5. It provides a complete and fine-grained Java metamodel where any program element (classes, methods, fields, statements, expressions...) can be accessed both for reading and modification.
http://spoon.gforge.inria.fr/

Alma - Multi-language software workshop for modeling, analyzing. Reads several languages, and outputs. Designed for object-oriented modeling (definition of classes and relations) and for migrating (to help convert) old code in older languages. Meets 2 needs: have a simplified software modeling workshop for small projects; make easier rewritings, ports, encapsulating non-OO code.
http://www.desnoix.com/guillaume/alma/

The Dynamo Project - Compiler architecture dynamically optimizes stand-alone programs via staged compiling. Uses run-time values and invariants to improve code as it executes, yielding performance superior to statically optimal code.
http://www.cs.indiana.edu/proglang/dynamo/

TXL Source Transformation System - Rule-based structural transformation is utilized as a paradigm for rapid generation of complex programs.
http://www.cs.queensu.ca/~cordy/

CCured source-to-source C translator - CCured is a source-to-source translator for C. It analyzes the C program to determine the smallest number of run-time checks that must be inserted in the program to prevent all memory safety violations. The resulting program is memory safe, meaning that it will stop rather than overrun a buffer or scribble over memory that it shouldn't touch.
http://hal.cs.berkeley.edu/ccured/