TCAD is a suite of programs for IC process and device modelling developed at Stanford University; older versions of the programs are available under an open-source license.
http://www-tcad.stanford.edu/
Links to research groups in Embedded Systems, Hardware Software Codesign, high level synthesis.
http://www.4bearsonline.com/sumitg/cs/CadPages.shtml
Focuses on the theory, analysis, design (computer aided design), and practical implementation of circuits, and the application of circuit theoretic techniques to systems and to signal processing.
http://www.ieee-cas.org/
SPICE 3 User's Manual converted to html format with search facility and cross-references added.
http://newton.ex.ac.uk/teaching/CDHW/Electronics2/userguide/
OPENCORES.ORG hosts a repository of free, open source IP cores (chip designs, System-on-a-Chip) and supplemental boards.
http://www.opencores.org/
http://www.geda.seul.org/