The Second Amendment Research Center of The Ohio State University is building a website to advance the study and discussion of the Second Amendment. Included, under "The Debate" tab, is an excellent discussion among scholars from varying perspectives of the historical and legal meaning of the Second Amendment.
About.com provides a useful list of state gun laws.
The Institute for Legislative Action is the political lobbying arm of the National Rifle Association. Its take on the current issues, pending legislation, and guns laws is available here.
The Brady Center to Prevent Gun Violence is the largest gun-regulation advocacy and lobbying group. Its take on the current issues, pending legislation, and guns laws is available here.