Areas with significant traditional presence of linguistic minorities in Greece (Arvanitika, Albanian, Aromanian, Megleno-Romanian, Macedonian Slavic, Pomak Bulgarian, Turkish, Ladino) 
General outline and idea after a map at Ethnologue ([1]) complemented and with some corrections from other sources:
Aromanian data from Image:South-Balkan-Romance-languages.png by Yuri Koryakov, Wikipedia version of published work by the same author: Koryakov Y.B.: Atlas of Romance languages, Moscow, 2001. Map #8; based in turn on data in Kramer J. Rumnisch: "Areallinguistik II. Aromunisch", in: Lexikon der romanistischen Linguistik, ed. G. Holtus, M. Metzeltin, Ch. Schmitt. Tübingen, 1991, Bd. III.
Further data from Euromosaic, Le [slavo-]macédonien / bulgare en Grèce [2], L'arvanite / albanais en Grèce [3], Le valaque/aromoune-aroumane en Grèce [4], and Mercator-Education: European Network for Regional or Minority Languages and Education, The Turkish language in education in Greece [5].
Cf. also P. Trudgill, "Greece and European Turkey: From Religious to Linguistic Identity", in S Barbour, C Carmichael (eds.), Language and nationalism in Europe, Oxford University Press 2000.
Albanophone villages near Florina according to: Riki Van Boeschoten (2001): Usage des langues minoritaires dans les départements de Florina et d’Aridea (Macédoine). Strates online, 10. [6]
Own work
Future Perfect at Sunrise