This book is excellent. It deals with why we need domain specific modeling (DSM), starting off with business value- then defines DSM and provides an architecture for it - the language, the models, code generation, a framework and the process that connects all of these. It follows this with 5 detailed case studies and then towards the end talks about uses and tools.
I enjoyed reading it and am planning to implement in my projects. The authors are associated with a tool that does DSM - Metaedit+ found at metacase dot com and which has a trial download.