Basically the website below directs you to an astroid impact calculator. In the website's own words:

Welcome to the Earth Impact Effects Program: an easy-to-use, interactive web site for estimating the regional environmental consequences of an impact on Earth. This program will estimate the ejecta distribution, ground shaking, atmospheric blast wave, and thermal effects of an impact as well as the size of the crater produced.

I find it interesting. Even though it only gives an estimate from a resulting astroid impact, it is interesting to see what kind of local effect an impact anywhere on the globe with the stats you enter would have in your area.

http://www.lpl.arizona.edu/impacteffects/