No fallbacks. Instead of naively returning the first available type, mime-types simply returns false, so do var type = mime.lookup('unrecognized') || 'application/octet-stream'.
No new Mime() business, so you could do var lookup = require('mime-types').lookup.
All mime types are based on mime-db, so open a PR there if you'd like to add mime types.
API
All functions return false if input is invalid or not found.
mime.lookup(path)
Lookup the content-type associated with a file.
mime.contentType(type)
Create a full content-type header given a content-type or extension. When given an extension, mime.lookup is used to get the matching content-type, otherwise the given content-type is used. Then if the content-type does not already have a charset parameter, mime.charset is used to get the default charset and add to the returned content-type.
mime.extension(type)
Get the default extension for a content-type.
mime.charset(type)
Lookup the implied default charset of a content-type.