sim card for Greece, best value?

You plan to call to the US from Greece on a cellphone? Money to burn I take it. In Greece a cellphone is called a 'handy' and there are several major providers who all have special deals at different times. You would be better off checking them out when you get there rather than making a decision based on info that will be out of date by then.

If you want to make cheap calls, buy phone cards and use a public phone box. Much cheaper than a cellphone.

cell phones in Greece has become the main communication ,and almost in every street of Athens and many Greek islands you will find a shop of Vodaphone or Cosmote. A sim card goes together with every package like (Vodaphone's a la Carte) or Cosmote (Cosmocarta package with cheapest offer including sim card and an Alcatel mobile phone for 29,9 EURO!! ) . In most of the Greek islands all the local Greek telecome offices (OTE) sale packages and mobiles of Cosmote. Alternatively and probably the cheapest way is to make your telephone calls from the internet usinng www.call2.com you can do that from every internet cafe or a wifi hotspot if you have a wireless laptop.

Thanks so much for your help. Really appreciate it.

I agree with #1, prepaid phone cards (with a pincode) will be much much cheaper, especially for international calls. You can use public phone boxes but even cheaper is to use them from any private phone (like in a hotel room or whatever).