The following is a list of links that contain MIME information. I haven't gone through them all, so if you are looking for the correct MIME-type for a file check one of these:
Official
By extension
- http://www.freeformatter.com/mime-types-list.html#mime-types-list
- http://svn.apache.org/viewvc/httpd/httpd/trunk/docs/conf/mime.types?view=annotate
- http://www.webmaster-toolkit.com/mime-types.shtml
- http://www.stdicon.com/mimetypes (json formatted)
- http://fileformats.archiveteam.org/wiki/File_Formats
- http://www.garykessler.net/library/file_sigs.html
By magic
- http://en.wikipedia.org/wiki/List_of_file_signatures
- http://www.garykessler.net/library/file_sigs.html
- http://www.digitalpreservation.gov/formats/fdd/descriptions.shtml
- https://github.com/file/file/tree/master/magic/Magdir
- https://github.com/mate-desktop/mate-mime-data/blob/master/mate-vfs-mime-magic