A good application letter does more than introduce your resume. It introduces you and your qualifications and convinces whomever reads it that you are the best person for the job. It makes an employer or recruiter interested enough to give your resume the attention it deserves. Write application letters with this in mind and you'll have a greater chance to be called in for an interview.
Open the letter with a sentence that includes what position you're applying for and where you saw the position advertised.
Write a paragraph that highlights your skills and how they relate to the position. Mention specific achievements that make you the best candidate for the position.
Address any questions or issues that may arise from your resume in the next paragraph. For instance, if you're applying for a job that would require a significant commute, mention that you're planning to relocate.
Briefly explain why you're leaving your present position. Be positive. Employers don't want to hear your difficulties with a particular company, and may view you as a complainer.
Use your letter to illustrate your professionalism. Don't try to be cute or funny unless those are qualifications for the job.
Close your letter by expressing a desire to be interviewed and giving your contact information. Thank the addressee for taking the time to review your resume.
Keep it brief. Your application letter should not be more than one page long. Address your letter to the specific person who will be reviewing your resume. Use paragraph form, not bullets. Use the same font and paper as your resume.
Be truthful. Don't exaggerate.