Driving the 3 hours between Sydney and Canberra doesn't always lend itself to needing a break. However it's easy to add on an extra hour or so getting out of Sydney's central traffic, navigating the highways, accidentally going down tolls or stopping for groceries in Cabramatta (which often results in a pre-trip Vietnamese meal anyway). However if there is a desire for food or caffeine or toilet enroute, Goulburn probably represents the biggest place to stop in through.
After some quick online reading, I was actually hoping to get to The Roses Cafe - unfortunately they were closed for reasons unknown. Other cafes, Thai and Italian restaurants that were around didn't really appeal, so the second option on my list was Greengrocer.
This is actually a bike shop with a nice cafe area as well as some produce for sale too. There are bikes, bike shorts, some laptops and plenty of food around. The atmosphere is eclectic and quite nice. Food options include sandwiches, lots of salad options, some nice Greek meatballs and a solid list of gourmet pizzas. Everything is good without being spectacular, but easily satisfying for any reason you decide to stop by.