Some of our favourites at the moment:
Cotinus Royal Purple - the deep purple summer foliage now gives way to a more fiery shade
Witch Hazels - In the New Year, we will be enjoying the unusual spidery flowers and heady scent, but for now, these Hamamelis provide an intense show of foliage colour. http://www.gardeningexpress.co.uk/CatalogProducts.asp?Keywords=hamamelis
Something a bit different . . . . . . . . .
Startling coloured foliage of the Aronia, the berries of which can be used as a "super food" http://www.gardeningexpress.co.uk/ProductDetails.asp?ProductID=3346
Even our Hydrangeas are getting in on the act, this Hydrangea macrophylla certainly has a deep blush to it! http://www.gardeningexpress.co.uk/CatalogProducts.asp?Keywords=hydrangea