<Address> Voulis 44A, Plaka, Athens. Tel. 210-32.14.121.
A small taverna near Syntagma square. It is called "Oinomageirio to Paradosiakó" meaning "The traditional wine-and-food place". It was very busy during the lunch hours (in the photo above, the place seems a bit sad, but this was shot when we left, well after the lunch time).
Speciality is sea-food. We say also shell-fish, something I have never seen in restaurants in Athens. In the photo are the grilled sardines (€6). There are also meat dishes.
Two of us ordered the sardines, spicy cheese paste (left, €6), fried potatoes, boiled green-leaves (hórta), and a large bottle of water. Bread was included in the cover charge. Total was a litte less than €20. After the lunch, we were offered watermelon for free.
If you feel hungry near Syntagma square, but don't feel like eating at fast-food or tourist eateries, this is the place to go.
P.S. The above visit dates back to the summer 2006, and I can confirm that the place is still up and running in April 2009.