Big Future by the College Board is an excellent, comprehensive resource for college major and career planning.
The undergraduate application section from the Purdue Online Writing Lab contains advice from undergraduate admissions officials from all over the US, and information on writing effective application essays. http://owl.english.purdue.edu/owl/section/1/49/
The United States Department of Labor's Employment and Training Administration has information on post high school employment and education opportunities and federal grants. http://www.doleta.gov/youth_services/
From the United States Department of Labor, the Occupational Outlook Handbook is a good starting point for current data on career descriptions, current and projected needs and availability, education and/or training required and more. http://www.bls.gov/ooh/