There certainly is no shortage of Internet resources on violence and aggression. A recent Goggle search turned up 60 million hits for violence. Obviously to find the most relevant information you have to refine your search criteria. The other problem is the standard one with the Internet, namely that much of what is available is out-of-date, incomplete, misleading, ill-informed, or just plain wrong. A major task confronting education at all levels is how to create informed consumers of the web. Generally speaking sites maintained from universities, the federal government, recognized "think-tanks" or by recognized experts in the field are good places to begin, but even experts have their biases and complete reliance on "establishment science" may lead to your missing out on some provocative if not entirely trustworthy material.
The links given below are good starting points, but obviously this list is far from complete. If you encounter sites you think are worth sharing, please let me know and I will be glad to add them.
The sites below provide many links for information about violence with a focus on prevention.
The Violence Policy Center favors gun control and has many resources on the topic and links to pro- and anti-gun control sites as well as more general resources
The Federal Government and especially the Department of Justice and its subsidiary, the FBI, publish a number of reports and statistical databases on violence. Their web pages are probably the best place to begin hunting for data on violence in America. The sites are not always easy to negotiate, so you may have to do a bit of scrambling around to get the information you want.
Kenan Malik is perhaps the most articulate and least hysterical of the many critics of what we might call biological determinism -- the use of animal and genetic research as a basis for inferences about human nature.
Last year Scientia at Rice, an organization that sponsors lectures on a variety of topics dealing with science construed broadly, hosted several lectures on violence. The link below is to the Scientia page; streaming video of most of the lectures can be accessed through the site