I don't follow any sort of recipe, but just throw in whatever I feel like. Today I have some cloves, cinnamon stick, bay leaf, dried orange zest, and a piece of my precious and very expensive vanilla beans simmering about on the stove. I do have some co-op mulling mix that I scoop into a tea ball and drop in the pot.
Bring to a boil, then turn down and simmer for 30 minutes or so. I have a cinnamon stick all ready and waiting in mugs for me and P (when he gets home).
PS - I hear you can spike your cider, but I wouldn't know...
PPS - mulled wine is a whole other post and delicious drunk while sitting on a cushion under your Christmas tree...
PPPS - What else could I throw in to mull? Whole allspice?