For a quick demo check out json.go
The core parlex package defines common interfaces around parsing. Sub-packages exist to fulfill all of the interfaces.
The core package also implements some helpers than use only the interface specification.
A few highlights; The stacklexer provides a powerful, easy to use lexer that can reduce the complexity of a grammar. The regexgram package supports some regex operators when defining a grammar. The packrat parser is a fairly efficient parser that can handle left recursion.