http://gadm.org/ (Gadm) contains world wide administrative areas down to 2 or 3 levels under countries. For iKartan, municipalities for the whole world is downloaded.
Gadm database
The gadm database is created by the Geokettle script CreateGadmDB.kjb, basically just a SQL script
create schema gadm; CREATE TABLE gadm.gadm ( objectid integer NOT NULL, id_0 integer, iso character varying(5), name_0 character varying(50), id_1 integer, name_1 character varying(50), type_1 character varying(50), id_2 integer, name_2 character varying(70), type_2 character varying(50), id_3 integer, name_3 character varying(70), the_geom geometry, CONSTRAINT gadm7_pkey PRIMARY KEY (objectid ), CONSTRAINT enforce_dims_the_geom CHECK (st_ndims(the_geom) = 2), CONSTRAINT enforce_srid_the_geom CHECK (st_srid(the_geom) = 4326) );