It may be outdated, I welcome corrections and additions.
American Physical Society journals
APS journals: http://publish.aps.org/
APS PROLA Physical Review Online Archive:
http://prola.aps.org/
APS PROLA Xref search:
http://prola.aps.org/xrs.html
AAPT: American J. of Physics:
http://scitation.aip.org/ajp/
American Institute of Physics
http://www.aip.org/pubs/
Scitation sign-up page:
http://scitation.aip.org/journals/doc/MY-SCI/myPreferences.jsp
Institute of Physics http://www.iop.org/
IOP electronic journals:
http://journals.iop.org/
Optical Society of America:
http://www.osa.org/pubs/
American Chemical Society: http://pubs.acs.org/
UMI Dissertations and Theses: (you can search and look at titles without
ordering)
http://disexpress.umi.com/
Science Direct:
http://www.sciencedirect.com
Surface Science:
http://www.sciencedirect.com/science/journal/00396028
Surface and Interface Analysis:
http://www3.interscience.wiley.com/journal/2009/home
Wiley Interscience journals in physics:
http://www3.interscience.wiley.com/browse/?subject=PHYS
JSTOR General Science Collection:
http://www.jstor.org/
Google scholar: http://scholar.google.com/
Compound Semiconductors Online:
http://www.compoundsemi.com/
IEEE Photonics Technology Letters:
http://ieeexplore.ieee.org/xpl/RecentIssue.jsp?puNumber=68
IEEE J. of Lightwave Technology:
http://ieeexplore.ieee.org/xpl/RecentIssue.jsp?puNumber=50
IEEE journals (browse):
http://ieeexplore.ieee.org/xpl/periodicals.jsp
Laser Focus World:
http://lfw.texterity.com/lfw/
Optics Infobase (database):
http://www.opticsinfobase.org/default.cfm
NASA Astrophysics Data System:
http://adswww.harvard.edu/
Arxiv (online archive of mostly theoretical physics):
http://arxiv.org
Qmags.com: http://www.qmags.com/
(Scientific American, etc by subscription)
Quantum Information and Computation, online contents:
http://www.rintonpress.com/journals/qiconline.html
Royal Society:
http://royalsocietypublishing.org/
Springer Link (journals, books):
http://www.springerlink.com/
Taylor & Francis
books:
http://www.taylorandfrancis.com/
journals in physics:
http://www.tandf.co.uk/journals/sublist.asp
Virtual J. of Quantum Information:
http://www.vjquantuminfo.org/quantuminfo/
Qwiki (quantum info wiki)
http://qwiki.stanford.edu/