InformationWeek

Society For Information Management
SIM touts itself as a gathering place for senior IS types. The group has working groups that tackle specific issues as well as education and events.
Association of Computing Machinery
ACM, which has been around since IT involved an in-depth knowledge of vacuum tubes, gathers together students and professionals from across the IT spectrum, offering conferences, education, and local activities.
IEEE Computer Society
You're allowed to join the Computer Society if you have a deep interest in--what else?--computing.
Association of Information Technology Professionals
AITP, with roots back to the '50s, has historical ties to programmers but aims to provide all IT professionals education and other resources.

These focused organizations can benefit IT professionals with specific interests or challenges.

OMICRON
This group for East Coast senior-level IT execs is a good place to network with your colleagues if you work east of the Mississippi. It offers events, education, and tools.
Internet Engineering Task Force
Hook up with the movers and shakers of the Internet--network designers, operators, researchers, and vendors--and maybe even build an Internet standard or two.
Women in Technology International
Women, despite their widespread presence in IT, make up only 2% of its executive positions. The 6,000-member WITI provides career development, networking, and job-search resources for women looking for that executive slot.
WebGrrls
WebGrrls helps women interested in Internet and other technical positions to navigate the job field by providing opportunities for networking, job leads, learning, and mentoring.

If you can't meet peers face-to-face, talk to them online.

Executive Strategies Tech Center
A membership site for IT leaders involved in planning, executing, and managing corporate IT strategies, brought to you by InformationWeek Online and Planet IT.
SIM Communities of Interest
SIM's communities include the SIM Executive Exchange, Best Practices Council, and other working groups.
@Your Service
Omicron hosts this online meeting place on its Omicronet site, and is considering opening up entry to executives outside its membership.

Guides, indexes, and tools that can make landing a job easier.

Riley Guide
Considered by some to be the best place to start an online job hunt, this guide contains tips, resources, and links to job sites.
Career Planning Process
No career direction? This tool from Bowling Green State University can help you chart a path.
Jobtrak Job Search Manual
An exhaustive job-hunting guide compiled by Jobtrak and George Washington University.
Resumé Writing Center
Do you write down your accomplishments in present or past tense? If you're not sure, this Career Mosaic site steps you through the resumé creation process.
Yahoo! Employment
Yahoo! aggregates and helps to organize the bewildering array of online resources out there.
Thingamajob.com
Check out this site for industry info, resume and interview tips and to search and apply for jobs online.
The Best Job Hunting Tools
Well, maybe best is a strong word, but this site has compiled what it considers to be the top job resources on the Web.
The Keirsey Temperament Sorter
Just in case you were wondering why you didn't get along with your last three bosses.