1. Light the grill or heat the broiler. Thread the shrimp onto four skewers. Brush the shrimp with 2 tablespoons of the oil; sprinkle with the oregano, 1/4 teaspoon of the salt, and the pepper.
2. In a medium saucepan, heat 5 tablespoons of the oil over moderately low heat. Add the garlic and cook, stirring, for 30 seconds. Add the chickpeas, water, and the remaining 3/4 teaspoon of salt and heat until warmed through. With a potato masher, mash the chickpeas. Stir in 1 tablespoon of the lemon juice and the parsley. Cover to keep warm.
3. Grill or broil the shrimp, turning once, until just done, about 4 minutes in all. Meanwhile, spread both sides of each pita with the butter and grill or broil, turning once, until golden, about 4 minutes in all. Cut into quarters.
4. In a small glass or stainless-steel bowl, whisk together the remaining 2 tablespoons each of oil and lemon juice. Mound the chickpeas on plates. Top with the shrimp skewers and surround with the pita quarters. Pour the lemon oil over the shrimp and chickpeas.
Wine Recommendation: The ingredients here practically demand the citrus and herb flavors of a sauvignon blanc. A version from California will be a bit softer than the classic French Sancerre or Pouilly-Fumé, but in this case avoid wines labeled Fumé Blanc. Though also made from sauvignon blanc, they tend to be more oaky.