I make preserved lemons all the time and love them, so I'm kind of curious to try it with blood oranges, cara cara oranges, or even grapefruit.
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I've preserved Meyer lemons -- assuming you mean preserving in salt, rather than making preserves (like marmalade). They're wonderful! But I have no experience with salt-preserving other, sweeter, citrus fruits.
I recently made Preserved Limes with fennel seed and turmeric, from a recipe in Dish magazine (New Zealand). They sit overnight with salt, then are packed with spices, bay leaves and crushed chilis in oil. They are supposed to be processed. I didn't take that step, just let them rest for a month, so I can't say the results are what they are supposed to be. The rind is still very hard, so I will try using them in cooked dishes. Very pretty and enticing!
Yes, you can do pretty much anything, but the thinner the peel, the better and quicker it works.
I posted my process for grapefruits, oranges and limes on my site. Here's the link: http://phickle.com/?p=674
Limes work exactly as lemons do. Grapefruit and orange take a little tweaking (clementines work well).
Many people do kumquats, but I don't see the point, to be perfectly honest, since you already eat the peel. I guess the point in that case would be the old reason, actual preservation of overabundance.
I hope this helps!