I love to come to Foster's on the weekend. They got wonderful breakfast, especially the streusel cake is phenomenal. They herb biscuits with cheese are a stomach filler and the coffee is exceptional.
Beware - it does get crowded, so if you are alone or just a couple of people, you may want to select one of the smaller tables, because table sharing is standard are Foster's. I find this to be one of the charms of the place.
I have to admit, I have never been there for lunch or dinner, but the menu for those times looks also good.
During exam time, you will find Duke students completing their take home exams there. But don't worry talking is still allowed and sometimes encouraged - a great stress relief for the students.
Give Foster's a try and don't be shy about sharing tables with complete strangers, you may find out that making friends at this place is really easy.