This map uses data from 'Ethnologue: Languages of the World', and shows the number of languages considered indigenous to each country that are still spoken there. Due to issues of language identification (see technical notes), it is possible to dispute the data used here, and a review of Ethnologue by Campbell and Grondona (2008) does just that; they claim "... the number of indigenous ('living') languages of different countries is inflated ...".
However, the map presents a good picture of linguistic diversity. Papua New Guinea has nearly 10% (820) of the world's indigenous living languages, so that there are only an average of 7000 speakers per language living there. Indonesia (737), Nigeria (510), and India (415) also have a large number of native languages.
At the other end of the scale, Belarus, Maldives, DPR Korea and Holy See each have only one indigenous living language.