Recycling citrus

I have some latent Depression-era delight over making good use of food that you'd normally throw away. And since we're all about recycling, why not make the most of your peels? Here are a few ideas for turn rinds into riches (beyond the delicious candied peels).

Make them into a powder to sprinkle on roasted meats or baked goods
Make limoncello
Make a candle