Cafes, light food, treats
Café Cafico: 11/4 block north on 58 street from the casa. The owner Federico makes delicious expressi and capuccini from organic coffee from Chiapas and Veraccruz. Beans are roasted on site, and make a great gift to take home.
Jugos de David: In nearby Mercado Santana. A great selection of juices and fresh fruit, as well as granola and yogurt.
Tala Café: Located in the Hotel San Angel just down the street and around the corner, is a wonderful place for breakfast, lunch and pasteries. They also have free wifi.
Olive Café Stop: Paseo de Montejo between 39/37, just down from the wonderful ice cream place mentioned next. A great place for coffee, snacks and ice cream. It's also a favorite gathering place for local ex-pats. Free wifi is available. Also see their blog...
Sorbeteria Colon: Paseo de Montejo. The tastiest sorbets you've ever tried, in all sorts of exotic flavors including mamey, pitaya, chirimoya, etc.
Restaurants
For an extensive list and some reviews see:
http://www.yucatanliving.com/category/merida-restaurants
and
http://www.los-dos.com/local-review/index.php