I'll list some more fares on Aegean/Olympic for the 4-segment hunters. Those are the cheapest available one-ways in economy I've stumbled upon:

SKG-HAM €32 OTA / €37 A3 site
SKG-BER €35 OTA / €38 A3 site
(Whoever lives in Germany, I'm jelly.. those prices... damn, I'd go every month to Greece)

SKG-MXP €34 OTA / €36 A3 site

Domestic:
HER-ATH €25 A3 site
KGS/SKG-ATH €30 A3 site

One ticket, multiple segments:
BLQ-ATH-LHR €61 A3 site
SOF-ATH-LHR €56 A3 site
TIA-ATH-LHR €55 A3 site

Also:
SOF/BLQ/BEG-ATH-OTP/IST/ADB/CFU/HER available for similar prices