Loads. Back in 1999 I built an entire suite of DSLs for generating web applications - you described objects, properties, validation rules, newsletter settings, commerce functionality, forum rules, etc and it used some combination of compile time code generation and run time parsing to deliver the functionality, substantially decreasing the dev overhead in building "good enough" web apps.
I will also note, that while it's possible to build a parser generator for external DSLs, for many use cases concrete syntaxes with existing parsers work fine. Back in 2000 I created a set of DSLs for generating web applications and I used the concrete, serializable syntax of XML as I got the capacity to describe types fairly clearly and I didn't need to generate a parser (or more importantly, an IDE plugin with auto complete and type validation). I figured I could always write a lightweight interface to display the info from the concrete DSLs to save business users from the angle brakcets. Json would allow you to do the same these days.
