It's great on sandwiches/paninis or sauteed like spinach or in soup or in eggs or on pizza....Anthony's Coal Fired Pizza in Fort Lauderdale makes a cheese pizza & then they toss arugula in an oil & vinegar dressing & fresh parm then it is set on top of the pizza...it is awesome. (The cheese is a blend of cheeses...not positive which ones). I am drooling just thinking of it.
I love it on sandwiches - especially Italian types like subs with salami, cappicole(sp?) ham, provolone cheese, pickled vegetables etc., etc. I've also occasionally tossed it into mixed vegetable stirfries, & have used it in certain pasta dishes as well. In fact, here's a link to one of my all-time favorite pasta dishes using Arugula, from well-known cookbook author & New York Time's food section contributor Mark Bittman:
"Farfalle with Gorgonzola, Arugula, and Cherry Tomatoes"