I would love that recipe, I'm in love with madelines, even bought the pan

Definately, I use it all the time!

We did it this week for the clementine pound cake: http://www.food52.com/recipes/9322_clementine_pound_cake. Delicious.

Yup! It's easier to zest cold fruit so you might want to stick them in the fridge first. (It's easier to juice room temperature, though.)

Agree - it's yummy, and to my taste, more interesting than orange. The only thing to watch for when you're zesting is to go lightly and not go too far into the pith. The zesty layer is much thinner and the skin can rip pretty quickly if you're overzealous (voice of experience here).

Yes, use it--it's lovely. Think tangerine zest.

Yep. Tastes a bit more tangeriny, but similar to orange zest.