A cover letter does more than complement a resume - it plays a vital role in helping you achieve your goal of expanding your horizons and reaching your potential.
Many people make the mistake of being redundant in their cover letter and resume.
An excellent cover letter is one that enhances, not mirrors the resume. The main purpose of the cover letter is to introduce yourself and your resume to the employer. The cover letter should broadly highlight your skills, while the job of the resume is to define those skills and explain how they will benefit the employer. For example, a cover letter will show the employer that you have excellent sales and customer needs assessment skills, while the resume will tell them that in 1999, you were named one of the top five salesman in the company. The cover letter told of your skills and the resume expounded and defined them.