Mace comes from the same plant as nutmeg. Mace is the stuff around the outside of the seed which is the nutmeg.
The flavour of mace is similar to but more delicate than nutmeg – some say it is sweeter but I don't think there is much difference really. I first came across mace in a recipe for a Thai curry paste.
Oil of mace has been used traditionally to cure insomnia – I wonder if that works!
Mace has been used for a long time in British cookery in potted shrimp.
In Europe you find mace in pates and sausages – particularly boudins blancs. You also find mace in baking and sweet dishes.
Of course, any dish with nutmeg in it can be done with mace instead.
If you can, buy it in its original form rather than ground. It doesn't keep that well for long in ground form.
BIBLIOGRAPHY - with thanks to Auckland Libraries
Cook's Encyclopaedia of Spices by Sallie Morris & Lesley Mackley
Discovering Vegetables, Herbs & Spices by Susanna Lyle
Spice Market by Jane Lawson
Spicery by Ian & Elizabeth Hemphill
Spices & Natural Flavourings by Jennifer Mulherin
Spices by Sophie Grigson
Spices Condiments and Seasonings by Kenneth T Farrell
Spices, Salt and Aromatics in the English Kitchen by Elizabeth David
The Cook's Companion by Stephanie Alexander