Preheat oven to 350 degrees F. Spray cookie sheets with nonstick cooking spray.
Place the cake mix in a large mixing bowl with the softened butter, eggs, and lime zest. Blend with an electrc mixer set on medium-high speed for 1-2 minutes, until smooth. Stir in the white chocolate chips with a wooden spoon until well mixed.
Drop dough by teaspoonfuls, 2 inches apart, onto prepared cookie sheets.
Bake for 10 to 13 minutes or until set at edges and just barely set at center when lightly touched. Cool for 1 minute on cooke sheets. Transfer to wire racks to cool completely. Prepare lime icing. Drizzle icing over cooled cookies.
To prepare the icing place the confectioners' sugar in medium bowl. Mix in zest and enough juice as needed to make icng just thin enough to drip off fork.
If you want lemon or orange cookies be sure and substite the flavor of choice in place of the lime zest and juice. I also sprinkled my cookie with finely chopped nuts after the icing was on the cookies but before it sets up.