Here's a simple cover letter for social media specialist. You should modify this cover letter according to your experience and qualifications.
I read your ad on Jobs Online and I'm very much interested to apply as a Social Media Specialist.
I can manage a decent number of websites and social networking accounts plus oversee all twitter and Facebook fanpages. I can also run linkbuilding campaigns and follow through with blog comments on a daily basis.
I am thorough and a fast worker as I am able to work well with minimal supervision.
You may view my portfolio at: http://linksocial.com
My monthly salary requirement is $750 (negotiable)
If you are interested in my services, please contact me at email@example.com
I welcome your online interview via Skype.
Thank you very much,