In a medium bowl, toss shrimp in chili powder. In a medium, non-stick skillet heat olive oil on medium heat. Add juice from 1/2 a lime, and heat. Add shrimp to pan and cook 1-2 minutes on each side. Do not overcook! Remove from pan to serving dish, sprinkle with lime zest and squeeze remaining half of lime over the top. Serve immediately.
Notes
If you're serving cold, squeeze the remaining 1/2 lime on shrimp immediately after cooking. Do not add zest. Chill completely. Before serving, sprinkle with lime zest and squeeze juice of another 1/2 of a lime over all.