I attended a wedding this weekend where guests' allergies were addressed in a discreet -- yet effective -- way. The caterers had marked the place cards with codes for different dietary needs (PA for peanut allergy, GF for gluten-free, V for vegetarian) so that at a glance, everyone who served anything to someone at a seat could tell whether there were any unique needs at the table.
While I've been to catered events that were responsive to dietary needs and worked with caterers that were unusually knowledgeable about allergies and other restricted diets, this was one of the most clever and effective solutions I've seen for balancing the need to get meals out efficiently and to indicate who needed the few special plates the kitchen had prepared. Highly recommended if you're planning a wedding where not everyone can eat off a set menu!
