Here's a helpful bit of info courtesy of tech-recipes - you can search for files on Mediafire using Google:
To look for music files, use this:
Google: site:mediafire.com mp3|wma|ogg
For a specific artist, include the artist's name:
Google: site:mediafire.com mp3|wma|ogg daughtry
For a specific song, include the song name:
Google: site:mediafire.com mp3|wma|ogg "over you"
For video files, use this:
Google: site:mediafire.com asf|rm|avi|mp4|wmv|flv
For Comics, use this:
Google: site:mediafire.com cbr|cbz
Google: site:mediafire.com cbr|cbz hulk
For archives:
Google: site:mediafire.com rar|zip