http://www.bbc.co.uk/food/recipes/database/lemonmeringuepie_6314.shtml
This recipe does take a while, and many stages, but it's well worth it. It was one of the nicest things I've made; the only change I'd make was to use 2 egg whites and not 3 as per the recipe for the meringue. I imagine it's because 3 egg yolks are used in the rest of the recipe. If you do do this, don't forget to use less sugar!