Commercial Services

ACM Digital Library - 54,000 on-line articles from 30 journals and 900 proceedings of the Association for Computing Machinery. Free bibliography, some abstracts.
http://portal.acm.org/dl.cfm?coll=portal&dl=ACM&CFID=975475&CFTOKEN=35520188

IEEE Xplore - 650,000 on-line articles from 12,000 journals or conferences. Different levels of subscription are possible.
http://ieeexplore.ieee.org/

IEEE Computer Society Digital Library - On-line access to 18 IEEE journals and to the proceedings of 150 conferences in computer science. Free access to abstracts and bibliography.
http://www.computer.org/portal/site/csdl/index.jsp

IngentaConnect - Online articles from over 30,000 publications. Abstracts are free; full text is available by subscription or pay-per-view.
http://www.ingentaconnect.com

FirstSearch - Access to on-line publications and citations including computer sciences (for all fields: 11000 full-text journals, 75 databases and citations from 12500 journals).
http://www.oclc.org/firstsearch/

Science - Computer Technology databases - List of (bibliographic) databases in computer sciences.
http://library.dialog.com/bluesheets/html/bls0017.html#SB0017

Safari Bookshelf - Electronic reference library for programmers and IT professionals. The subscription service lets you search, annotate, read and build your own reference collection online.
http://safaribooksonline.com/

Inspec - English-language bibliographic information service providing access to scientific and technical literature in physics, electrical engineering, electronics, communications, control engineering, computers, computing, information technology, manufacturing and production engineering.
http://www.theiet.org/publishing/inspec/