I've been looking at some of the other recipes around here to see changes I want to make and I've noticed some guys going with cocoa powder or cocoa nibs because the fat in chocolate can affect head retention.
I don't remember specifically having this problem, but I am considering switching to cocoa. I think I slightly over-primed so that may have made up for it. Also, I'm planning on using 2 lb of barley flakes and 1/4 lb of wheat flakes, so I don't know if head retention is going to be a huge problem.
Here's the Ginger Cookie Ale:
10.5 lb 2-row
0.5 lb dark crystal
1.15 oz whole perle (60 min boil)
1 cup molasses (added near end of boil)
0.5 cup brown sugar (added near end of boil)
Wyeast 1098 British Ale
Added to secondary:
2 cinnamon sticks
4 cloves
roughly 1-2 oz grated fresh ginger
Primed with 1 cup brown sugar
I'm not positive on the ginger. It was last year, and I eyeballed it, so I can't tell you exaclty. Don't go crazy unless you really like ginger. My best guess for your typical 5 gallon batch would be not to go much more than 1 - 1.5 oz. I couldn't tell you what volume that would be, or how much dried ground ginger that would be.
Again, I can't give you a detailed review but this one also turned out nicely. The only problem was that I don't think I mixed the priming sugar in very well and some of the beers were flat. It's basically a simple Pale ale (or maybe a brown ale) recipe, minus the aroma hops, with the molasses and sugar added, then spiced in the secondary. Like I said with the stout, the fact that you are doing extract shouldn't matter much as long as you use a good base recipe, and make any minor adjustments like omitting (or reducing) the aroma hops.
Hopefully I can get started on this year's batch of Christmas beers this week and if they turn out well, I'll post the new recipes in about 2 months.