What I thought I could do would be to dry them and use them as Christmas decorations/to scent the air.
It's simple and it goes like this...
Step 1: Collect your oranges/lemons
(mine was one of each because that's what I put in that batch of mulled wine)
Slice into 1cm thick slices (about half an inch) or slightly thinner if you're good with a knife, I'm not.
These are not the fruits I used, just an illustration. I used heavily stained red ones.