Though all cover letters are different, there is some basic information that should be included in each:
The job you are applying for:
The job posting source
Any referrals or contacts
The location you desire (if applicable)
Your qualifications:
Experiences and skills that make you a strong candidate
Personality traits and competencies that would add to the company
Why you want to work for the company:
Purpose for choosing the company
How you will add to the company's mission and bottom-line
How the employer can follow-up with you:
Your contact information including address, email address and phone number.