www.careerswales.com - click on Tools and Resources and then Careers Search. Provides a detailed description of hundreds of job, plus qualifications needed, training routes, skills and qualities for entry. They also have an 'ideas quiz' for career ideas that may suit you.
www.brightknowledge.org - clear articles about different jobs, typical days, entry requirements, pay and the best & worst bits about the job.
Volunteering and Work Experience:
www.gap-year.com - everything you need to know about taking a gap year at home or abroad.