Table of the Nuclides (at BNL) - Masses and reaction data for all nuclides across the periodic table.

Table of the Nuclides (at LANL) - Containing Moller and Nix evaluation as well as experimental data

Physical Review C - Major Journal of Nuclear Physics. All articles back to volume 1 in 1970 are available for download.

Journal of Physics G - Nuclear and Particle Physics Journal from the Institute of Physics (UK)

Nuclear Theory section of arXiv (lanl) preprint server - About half a dozen new articles in nuclear theory get submitted here every weekday, most of them en route to paper journals. Archives go back to 1992 and can be searched.

Nuclear Physics A - Journal covering Nuclear and Hadronic Physics.