I corrected a minor error in the 2004 map: a municipality in Epirus was actually a draw between the PASOK and the ND.
Here is 2007:
Some interesting trends I can't explain due to my limited knowledge of the Greek political scene like the ND breakthrough in Western Crete or the massive swing from the ND to the PASOK in Eastern Thrace compared to 2004 when, for some reason, the ND won there big in this traditional PASOK stronghold.
The island with the two red municipalities is Ikaria, isn't it? Which were the strongest places for the KKE, in the mainland and the archipelago?
Yes, the island with two red municipalities is Ikaria. Otherwise, the KKE was stronger in 2007 in Lesbos, Samos, Thasos, the Ionian Islands (especially in Corfu) and, to a lesser extent in Lemnos. On the mainland, the party got its best results in the popular suburbs of Athens and Thessaloniki, in Thessaly, and in the former prefecture of Ioannina. Conversely, the KKE was weak in Crete, in Western Thrace, and, to a lesser degree, in Peloponnese.
Why is (was) the island Crete do leftist?
I have only a superficial knowledge of Greek politics so I can’t give you a clear and comprehensive answer. One of the explanations seems to be that the PASOK successfully captured the traditional venizelist (liberal, centrist and republican) vote, which is traditionally strong in the island (Venizelos was born in Crete). In addition, the PASOK has faced in Crete little competition from the left, especially from the KKE, which has been historically weak in the island (notably, there was no important communist guerrilla activity in Crete during the Greek Civil War). Things have changed however and nowadays, SYRIZA has displaced the PASOK as the largest party in Crete.