• All DOE labs: http://science.energy.gov/wdts/scgsr/
• Berkeley: http://cs.lbl.gov/careers/summer-student-program/
• Argonne (Chicago): Givens, Cody
• Sandia (New Mexico and CA): http://www.sandia.gov/careers/_assets/documents/StudentPrgmFlyer_MECH.pdf
• Los Alamos (NM): http://www.lanl.gov/careers/career-options/student-internships/graduate/
• Livermore (CA): http://students.llnl.gov/, High Energy Density Physics, Computation Student Intern
• Oak Ridge (TN): http://www.orau.org/ornl/graduate-students/
• PNNL (Richland or Seattle, WA), first link at http://science-ed.pnnl.gov/default.aspx?topic=Graduate_Students

Various Bay Area opportunities: https://career.berkeley.edu/Internships/IntCurrent (not the first, which is Berkeley only)