love the giant ooey-gooey cinnamon rolls from Main STreet Bakery (have found them at other bakeries in Disney, including some resort counter service...but the ones at Main Street Bakery are the biggest, and usually the freshest.) The Main Street cinn rolls are about the size of a dinner-size paper plate!
2nd the post by natebenma above...click on that link for the sticky all about snacks that have been allowed this year.
The unofficial rule of thumb (with some exceptions) is that any single-serving item priced under $4.00 will be allowed for a snack. This does not always hold true so if in doubt, be sure to ask before ordering.
Note it is always a single-serving, so you could see a bag of candy that's only $1.99 but if the label says it's 2 servings of candy they won't allow it for a snack credit.