Measuring software productivity by lines of code is like measuring progress on an airplane by how much it weighs. © Bill Gates
I once rewrote 30 000 lines of C++ code in 1000 lines of Ruby. Years passed, and shit hit the fan again. Today, I rewrote 424 lines of Java+Spring+Hibernate in 18 lines of bash. This is less glorious, but if you compare the size of the deliverable, it's 39Mb for the J2EE webapp against… 772 bytes for the shell script.
P.S. It is probably safe to say now, after 5+ years, that the C++ code was TopiEngine and my rewrite was tm4r. The latest version of TopiEngine on launchpad has 67 279 lines of code. It doubled in size since I rewrote it in Ruby. My tm4r now counts 1 227 lines of code.
P.P.S. Of course, these rewrites are not exact functional replicas. tm4r is an in-memory engine, TopiEngine uses sqlite underneath, so their usage patterns may differ wildly. Same with the Java → bash rewrite. But for the task at hand, there was always a reason to rewrite, and the reason was directly related to the code bloat, modifiability and maintainability.