U.S. Citizenship and Immigration Services
Provides information about visas and employment options for foreign nationals. 

US Remac, Inc. 
Employment service for international students seeking to work in the U.S. with companies that will sponsor their visas. (in Japanese)

VisaJobs
This web site is dedicated to finding employment for foreign nationals wishing to live and work in the United States and Canada. Provides a free listing of employers accepting H-1B Visa holders, as well additional access to job listings for a fee.

VisaNow.com

W3Visa

W3ViSA is a web portal centered on U.S. Immigration.  Whether you are a U.S. employer, a job seeker, a student, or a temporary visitor, W3Visa provides a place for you to get your U.S. immigration tasks done.
Lists tens of thousands of U.S. employers who have sponsored employees for H-1B visas. Includes immigration news. Allows job seekers to post resumes and search for jobs.