The Cognitive Science major provides an excellent background for those interested in pursuing any number of careers.
Here are some references to help you achieve the three C's: Clarity (what you might like to do), Competitiveness (the skills necessary to achieve your goals), and Connections.
Clarity
Know Thyself
Tang Center Career Counseling Library
Read about careers with a social impact
Podcast about branding as an exercise in self-reflection
Visit the Career Center for in-depth career counseling
Know the World of Work
Massive repository of advice about the workplace
Another massive repository of great information about the modern workplace
The blog at LinkedIn has some great articles about all aspects of work
Connections
@Cal Network connects students with alumns
Learn how to become a master informational interviewer
Use LinkedIn to your advantage
Competitiveness
Get an internship: It's the best way to increase your competitiveness and marketability
Volunteer (It's really a lot like interning when you really think about it)