One small nit on the Go example code:

  func (wordTotals *WordTotals) Update(word string) {
        total, found := wordTotals.WordTotals[word]
        if !found {
            total = 0
        }
        wordTotals.WordTotals[word] = total + 1
  }

Can be done as:

  func (wordTotals *WordTotals) Update(word string) {
        wordTotals.WordTotals[word] += 1
  }

(thanks to Go default values)