Panini

An electric grill, of the style popularized by a famous boxer, can be had cheaply second-hand. It can substitute for a panini press if you don't mind the grill marks. Here are some different sandwiches that have worked well:

tomato slices (dried if possible)
red onion slice
salami
pepperoni
pastrami
provolone cheese
mayo
oregano
crushed red peppers
Italian 9-grain bread

tomato slices
sweet onion slice
salami
pepperoni
ham
provolone cheese
pesto
marble rye