Is there any such thing as a Integrated Development Environment for context free grammars (or any variant on a formal, machine parsable grammar) that target natural languages? The ones for BNF grammars seem to be overwhelmingly aimed at turning language into machine executable code. I would imagine that a similar tool for natural language would let the user write a grammar, evaluate it for mistakes and parse example sentence to trees or generate sample sentences given a dictionary of lexemes/tokens.
ANTLR allows you to write BNF context free grammars (which also produces code).
ANTLRWorks allows you to try examples strings on the grammar and displays the parsing.
As to natural language, if you have a BNF grammar for one (I think there is a non-trivial but still non-inclusive grammar for English in the javacc parser code), then you can use it with some changes with ANTLR.
You may find this interesting: LingBench IDE.
From the product description:
LingBench IDE is an Integrated Development Environment for Linguists and Computer Linguists to Model a Natural Language by describing the morphology, the syntax, the lexical and other aspects of a language in detail.
It seems to be an old and unsupported piece of software though.