While looking for ways to neatly map 'unmapped keys' in my structs, I came across the following: * http://devel.io/2013/08/19/go-handling-arbitrary-json/ * https://godoc.org/labix.org/v2/mgo/bson#Marshal Basically, it implements an `inline` tag that is then used to read all of the extra fields into a `map[string]interface{}`