High Energy Physics
As you can see, this web site is hosted by the CERN organization, that is the European center for the research in nuclear and subnuclear physics. CERN is where the World Wide Web is born, so take a look at its main site!
For the high energy physics research, CERN offers also several among the most important facilities all around the world. In particular, the Large Hadron Collider (LHC) is the biggest particles accelerator in the World. The ATLAS experiment is one of the main LHC experiments.
Among the most useful web sites for high energy physics is the online version of the Particle Data Book, from the Particle Data Group. Another link I often use is the HEP Preprint Servers page.
Other two really useful sources are The Particle Detector BriefBook by R.K. Bock and A. Vasilescu, and the The Data Analysis BriefBook by R.K. Bock and W. Krischer.
When I don't remember a formula or a mathematical theorem, I usually look at the Handbook of Mathematical Functions by Abramowitz and Stegun, or go to the Eric's Treasure Troves of Science (expecially useful for mathematics). Finally, when you have to search for a particular argument, you may find help in the Physics and Astronomy Classification Scheme (PACS).
Cosmic Rays Physics
There is a number of experiments that measured, are measuring or will measure the CR features, and this site contains the links to most of them. In addition, you are kindly invited to look at the AMS experiment site.
You will find a huge amount of informations about cosmic rays browsing the proceedings of the International Cosmic Ray Conferences: ICRC1999, ICRC2001, ICRC2003, ICRC2005, ICRC2007.
Other links
Statistical data analysis: first, the "Introduction to Probability" course by Grinstead and Snell, and Jaynes' book, then the proceedings from the conferences PhyStat2003, PhyStat2005, PhyStat2007, PhyStat2011.
Physics related computing items, from CERN: first, the C++ framework called ROOT, then the (old) FORTRAN numerical and statistical libraries developed at CERN since the seventies (CERNlibs). We can also find the PAW and PAW++ interfaces to HBOOK, MINUIT and other parts of CERNlibs.
If you are interested in the detector simulation, note that the FORTRAN GEANT3.21 framework has been substituted by a new C++ version called Geant4.
You can even get a live-DVD containing a Linux distribution and a lot of scientific software: simply visit www.paipix.org!