I made one that turned out great - I just drank the last one last night.
I used a mix of sweet orange peel, cardamon, ginger and cinnamon (I don't have the exact amounts of each handy - if I remember to do so, I will edit that in later) and was really happy with the results.
I didn't boil the spices. I put them into a hops bag and put them into the wort (a partial boil) during cooling. I cool my wort by partially immersing in ice water in my kitchen sink. I took the bag of spices out when I dumped the wort into the fermenter.
Slightly off topic - I always use a blend of hop varieties.