A useful, broad search for standards, usually without access to full-text.
(UIUC Patrons Only)
The ASTM Standards and Engineering Digital Library contains standards and technical engineering information covering a broad range of engineering disciplines.
SAE often reissues their standards as Technical Papers. If the standard you are looking for is not available as a Technical Paper a hardcopy may be at the Engineering Library.
IEEE Xplore Digital Library provides access to journals, books, papers and standards published by IEEE which includes some AIEE & ANSI standards.
Occupational Safety & Health Administration Law and Regulations page includes current standards.