If you are looking for a vegetarian way to get the crunch factor, consider adding crispy onions or raw bell peppers for a similar textural effect, or crumble some tortilla chips ... Any pickled ...
Other favorite veggies I've seen added are finely chopped onion and celery, which add flavor and crunch. Chopped pickles or relish seem to be popular in egg salad too, but be careful to drain them ...