Question
North shore of Long Island, New York
Due to recent renovation on my neighbor's house, I would like to plant something that will provide privacy.  It would have to be a tree that grows straight and narrow - as the space is not that wide.  I would love it to grow 20-30 feet like a tall skinny soldier - and if it could grow quickly too.  

Answer
The kind of tree you're looking for is called a "columnar" tree, and many species have been slectively grown for this quality - Here are a couple that will grow where you live:

Columnar Maple (Acer platanoides 'columnar') only gets 15 feet wide, but up to 35 feet tall.

Apollo Maple (A. saccharum 'Barnett Cole') only gets 10 ft wide by 25 feet tall

Skyrocket Colunar English Oak (Quercus robur 'fastigiata') gets bushy at the base, for a good screening effect, but will get up to 50 feet tall.

Columnar Sargent Cerry (Prunus sagenti 'colunmaris') has a lovely purple leafe and pink flowers in the spring

Crimson Spire Oak (Quercus alba x Q. robur 'Crimschmidt') gets 15 ft. wide x 45 ft tall

and finally, a

Corinthian Linden (Tilia cordat 'Corzam') also gets 15 x 45 ft tall, with a low skirt of branches.

There are more, but this should get you going.  Talk to your local nursery supplier if there are others available in your area... ~M