Software Migrations
Program-Transformation.Org: The Program Transformation Wiki
Software Migrations Ltd
Homepage: http://www.smltd.com/
SML use formal transformations to convert one form of code to another; they can work on anything from assembly language to high level requirements (e.g. Z specifications). They specialise in IBM assembler legacy systems, but also work with C and COBOL, and probably any language.
They claim that about 90% of the work of migrations can be automated (depending on various factors).
Their FermaT Transformation Engine is available for downloading.