Computer Science 

ACM
Association for Computing Machinery.

Apple Computer Inc.
A good source for Macintosh computing and software information.

CiteSeer: Scientific Literature Digital Library
Free full-text database of computer science papers made available by the NEC Research Institute.

The Computer Almanac
Interesting and useful numbers about computers.

Data Warehousing and OLAP
A comprehensive list of Data Warehouse and OLAP papers (with links to full papers), links, and conferences.

DevArticles
Programmers resource site with professional articles, news, tips, tricks, and eBook links.

Dictionary of Algorithms and Data Structures
From the National Institute of Standards and Technology.

IEEE
Institute of Electrical and Electronics Engineers.

Java
"The source for Java technology."

Linux Online
Everything you ever wanted to know about Linux... Microsoft Corporation
A good source for personal computing and software information.

Mozilla
Coordinates the development and testing of this "open source" browser by providing discussion forums, software engineering tools, releases and bug tracking.

Open Directory Project-Computers and Programming
Large, comprehensive human-edited directory of the Web. It is constructed and maintained by a vast, global community of volunteer editors.

Slashdot
"News for nerds."

Sun Microsystems
A good source of information in microcomputer and network technology.
Links to Computer Related Societies.