If my SQL is correct, the most common address name for a building in Finland is Rantatie (Shore road), if null values are excluded that is. According to my query*, there are a total of 5634 buildings residing along a road called Rantatie. The second most common address for a building is Kirkkotie (Church road), followed by Vanhatie (Old road), Koulutie (School road) and Keskustie (Central road).
Not the most interesting map, likely the buildings are where people are. Maybe calculating the proportion of Rantatie buildings per municipality or some such would be more interesting.
SELECT osoite_fi, count(*) FROM osoitteet.osoitteet_ei_null GROUP BY osoite_fi ORDER BY count(*) DESC LIMIT 5