Hi - you say startups, but have you considered going a bit larger? I work for a large mobile (~800 employees, NASDAQ listed) technology company whose co-founders were Greek, and our largest engineering team is in Athens. I know some of our products are Ruby based (not my department, I deal with native mobile apps).

If you want to get in touch with me I can forward your CV to the right people. Just checked and we're recruiting Athens based interns right now (and they're paid). Plus you'll get to do a lot of work with our offices in SF and London. Send me a DM on Twitter (@objclxt) and I'll ping you my e-mail.