Trail shoes are, for the most part, quite similar in construction to road running shoes. However, they have added traction and more durable uppersoles. Some road shoes work well as part-time trail shoes (e.g. the Saucony GRID Stabil -- see Top Motion Control Running Shoes below), while many trail shoes work well on the road (e.g. the Adidas Trail Reponse). Features to look for include: added traction, durability without too much weight, and motion control for running on uneven surfaces.
Adidas makes a great trail shoe, the AdiSTAR Revolt. Its predecessor the Trail Response was around for many years, and this is the update. This is the shoe I wear, and I wear it both for trail and road running. It offers a snug fit, and good feel--not so much of a trail shoe that you can't wear it on the road.
This is one of the newer shoes that I've listed here. New Balance has always made a good line of strong, sturdy, and well balanced shoes--you can add this one to the list. This is a lightweight model that feels good the first time you slip it on. It's very comfortable, and can be used for both road and off-road surfaces.