I'm currently working on GetInLine 2 - a complete rewrite of GetInLine, a record-processing DSL I wrote a couple of years ago.
The DSL is not yet as fluent as I would like, but I'm much happier with the underlying design. I'll also be switching to an Apache license; James Strachan encouraged me to do this for version 1, but I never got round to it.
I'm following the development approach that Steve Freeman and Nat Pryce advocate in their book (and which the three of us expound in our TDD course).
I started with a failing end-to-end test. Then I used mocks and unit tests to help me to pull the required interfaces into existence, filling out the application until the first end-to-end test passed.
The resulting code is much simpler to test and write than v1 was, and I've ended up with a highly pluggable set of components.
I'll post a URL as soon as GIL2 is ready for beta testing; if anyone wants to tale a look before then, let me know.