Carefully peel back corn husks, but do not remove. Scrub ears with stiff brush to remove silks. Rinse ears. Pull husks back up around corn. Place in large pot; cover with water. Soak 2 to 4 hours; drain well. Peel back husks and pat corn dry with paper towels.
For lime salt, in small bowl stir together lime peel and salt. Brush some of the butter on corn. Sprinkle lightly with lime salt and chili powder. Fold husks back around ears. Tie husk tops with strips of corn husk or 100% cotton kitchen string.
For charcoal grill, grill corn on rack of uncovered grill directly over medium coals for 25 to 30 minutes or until tender, turning and rearranging occasionally. (For gas grill, preheat grill. Reduce heat to medium. Place corn on grill rack over heat. Cover; grill as above.)
To serve, remove ties from corn; peel back husks. Pass remaining butter, lime salt, chili powder, and limes for squeezing.