Dr. D.H. Hubbers is something of the Richard Jaynes of Germany. His wonderful array of new hybrid Kalmia cultivars can be found here. 'Mitternacht' is a dark beauty, sure to come to the US.
http://www.kalmia.info/html/zuchtungen_-_cultivars.html

Speaking of Dr. Jaynes, his www.brokenarrownursery.com also offers a full range of the best Kalmia plus these other treasures:

• Acer rubrum 'Snowfire' - a very bright tricolored variegate, semi-dwarf
• Chionanthus retusus 'China Snow', Don Shadow's improved, dark-leaved clone
• Hamamelis mollis 'Gold Edge, a new creamy-yellow margined clone
• Hydrangea arborescens 'Terry Greer', huge cauliflower-like double flowers
• Magnolia zenii 'Pink Parchment', Dirr's light pink to blush clone, very early
• Zenobia pulverulenta 'Christoff'', a new bluish clone
• Metasequoia glyptostroboides 'Gold Dawn', a smaller version of 'Ogon'
• Sciadopitys verticillata 'Tumbleweed', slow, semi-loose Waxman clone

Baumschule Hachmann (www.hachmann.de) is world famous for their breakthrough Rhodie hybrids but they also often a number of rare trees and conifers from other genera. Some recent offerings include:

• Chamaecyparis nootkatensis 'Klippert', a blue weeper
• Chamaecyparis lawsoniana SILBERSTAR(r), A narrowish, blue tower of plumes
• Juniperus communis 'Green Mantle', nice dense green carpet
• Juniperus communis 'Rakete', super dense spire
• Pinus mugo 'Frisby', a very low prostrate plant
• Thuja occidentalis 'Konfetti', liberally splashed in cream
• Ilex aquifolium 'White Cream', huge cream centers to each blade