There is a series of little construction sites in Midtown. As of May 2003, seven buildings were under construction, and another 17 were proposed for the future. Some thirty big skyscrapers have been built in the last five years, and more are following.

Here is a map of these construction sites created by Stern from Wired New York (http://www.geocities.com/nyskyscrapers/Maps.html)
Note: Blue sites are under construction, while yellow sites are proposed for new buildings-