Are there any foods that a baby under 1 year old should avoid altogether besides shellfish and honey?

Food Safety is #1. Biggest thing is food safety & choking risk-anything that is a piece that could lodge in an airway should be avoided--stick to small pieces of soft foods he/she can mash with his gums or swallow. Avoid peanut butter 'cause of texture--it's no longer believed age of introduction correlates to risk of allergy. But if strong family history of food allergy, there may some foods you might delay.
No juice. Limiting or eliminating fruit juices from a baby's diet can help reduce obesity in children. Get the good habits started early.
Infant diet. Aside from honey, there really isn't a solid scientific basis for avoidance of food in infancy. Some experts feel this may actually increase the chances of food allergy. If there is a history of confirmed food allergy in a parent or sibling, then caution may be appropriate.