Oranges and Lemons (say the bells of St Clements) - and Limes, Grapefruit and Satsuma type oranges. Yum.
I love how the zest and the juice can be used in cooking, and that the juice can be drunk- obviously seeing as it is juice!- and that said zests and juice are equally at home in sweet desserts and savoury dishes. In fact a little citrus zest and / or juice can elevate all sorts of recipes to the sublime!
I do have recipes, but no pictures today and I hate posting the recipes with no visual aids so I'm not going to. Sorry. and the picture above is from Wikipedia.