Rick Bayless's shrimp with spicy chipotle-tomato sauce from the July issue of Food & Wine would be amazing over orzo. That's not how I had it - instead I chopped up the shrimp and turned it into a dip served with tortilla chips. It's pretty amazing, though, and even though it requires a few steps, it's not overly complicated.
Also delicious, and weeknight-with-orzo-friendly, Bon Appetit's chicken with mustard and herbs and sauteed radishes:
I couldn't find any tarragon (at Trader Joe's or Belvedere Square!) so I subbed in basil from my deck. Plus, I was a little low on radishes, but that was OK. This dinner was easy and very, very flavorful. And I actually did serve it with orzo!