mime.js

var types = {
    '.3gp'     : 'video/3gpp',
    '.a'       : 'application/octet-stream',
    '.ai'      : 'application/postscript',
    '.aif'     : 'audio/x-aiff',
    '.aiff'    : 'audio/x-aiff',
    '.asc'     : 'application/pgp-signature',
    '.asf'     : 'video/x-ms-asf',
    '.asm'     : 'text/x-asm',
    '.asx'     : 'video/x-ms-asf',
    '.atom'    : 'application/atom+xml',
    '.au'      : 'audio/basic',
    '.avi'     : 'video/x-msvideo',
    '.bat'     : 'application/x-msdownload',
    '.bin'     : 'application/octet-stream',
    '.bmp'     : 'image/bmp',
    '.bz2'     : 'application/x-bzip2',
    '.c'       : 'text/x-c',
    '.cab'     : 'application/vnd.ms-cab-compressed',
    '.cc'      : 'text/x-c',
    '.chm'     : 'application/vnd.ms-htmlhelp',
    '.class'   : 'application/octet-stream',
    '.com'     : 'application/x-msdownload',
    '.conf'    : 'text/plain',
    '.cpp'     : 'text/x-c',
    '.crt'     : 'application/x-x509-ca-cert',
    '.css'     : 'text/css',
    '.csv'     : 'text/csv',
    '.cxx'     : 'text/x-c',
    '.deb'     : 'application/x-debian-package',
    '.der'     : 'application/x-x509-ca-cert',
    '.diff'    : 'text/x-diff',
    '.djv'     : 'image/vnd.djvu',
    '.djvu'    : 'image/vnd.djvu',
    '.dll'     : 'application/x-msdownload',
    '.dmg'     : 'application/octet-stream',
    '.doc'     : 'application/msword',
    '.dot'     : 'application/msword',
    '.dtd'     : 'application/xml-dtd',
    '.dvi'     : 'application/x-dvi',
    '.ear'     : 'application/java-archive',
    '.eml'     : 'message/rfc822',
    '.eps'     : 'application/postscript',
    '.exe'     : 'application/x-msdownload',
    '.f'       : 'text/x-fortran',
    '.f77'     : 'text/x-fortran',
    '.f90'     : 'text/x-fortran',
    '.flv'     : 'video/x-flv',
    '.for'     : 'text/x-fortran',
    '.gem'     : 'application/octet-stream',
    '.gemspec' : 'text/x-script.ruby',
    '.gif'     : 'image/gif',
    '.gz'      : 'application/x-gzip',
    '.h'       : 'text/x-c',
    '.hh'      : 'text/x-c',
    '.htm'     : 'text/html',
    '.html'    : 'text/html',
    '.ico'     : 'image/vnd.microsoft.icon',
    '.ics'     : 'text/calendar',
    '.ifb'     : 'text/calendar',
    '.iso'     : 'application/octet-stream',
    '.jar'     : 'application/java-archive',
    '.java'    : 'text/x-java-source',
    '.jnlp'    : 'application/x-java-jnlp-file',
    '.jpeg'    : 'image/jpeg',
    '.jpg'     : 'image/jpeg',
    '.js'      : 'application/javascript',
    '.json'    : 'application/json',
    '.log'     : 'text/plain',
    '.m3u'     : 'audio/x-mpegurl',
    '.m4v'     : 'video/mp4',
    '.man'     : 'text/troff',
    '.manifest': 'text/cache-manifest',
    '.mathml'  : 'application/mathml+xml',
    '.mbox'    : 'application/mbox',
    '.mdoc'    : 'text/troff',
    '.me'      : 'text/troff',
    '.mid'     : 'audio/midi',
    '.midi'    : 'audio/midi',
    '.mime'    : 'message/rfc822',
    '.mml'     : 'application/mathml+xml',
    '.mng'     : 'video/x-mng',
    '.mov'     : 'video/quicktime',
    '.mp3'     : 'audio/mpeg',
    '.mp4'     : 'video/mp4',
    '.mp4v'    : 'video/mp4',
    '.mpeg'    : 'video/mpeg',
    '.mpg'     : 'video/mpeg',
    '.ms'      : 'text/troff',
    '.msi'     : 'application/x-msdownload',
    '.odp'     : 'application/vnd.oasis.opendocument.presentation',
    '.ods'     : 'application/vnd.oasis.opendocument.spreadsheet',
    '.odt'     : 'application/vnd.oasis.opendocument.text',
	'.oga'     : 'audio/ogg',
    '.ogg'     : 'audio/ogg',
	'.ogv'     : 'video/ogg',
	'.ogx'     : 'application/ogg',
    '.p'       : 'text/x-pascal',
    '.pas'     : 'text/x-pascal',
    '.pbm'     : 'image/x-portable-bitmap',
    '.pdf'     : 'application/pdf',
    '.pem'     : 'application/x-x509-ca-cert',
    '.pgm'     : 'image/x-portable-graymap',
    '.pgp'     : 'application/pgp-encrypted',
    '.pkg'     : 'application/octet-stream',
    '.pl'      : 'text/x-script.perl',
    '.pm'      : 'text/x-script.perl-module',
    '.png'     : 'image/png',
    '.pnm'     : 'image/x-portable-anymap',
    '.ppm'     : 'image/x-portable-pixmap',
    '.pps'     : 'application/vnd.ms-powerpoint',
    '.ppt'     : 'application/vnd.ms-powerpoint',
    '.ps'      : 'application/postscript',
    '.psd'     : 'image/vnd.adobe.photoshop',
    '.py'      : 'text/x-script.python',
    '.qt'      : 'video/quicktime',
    '.ra'      : 'audio/x-pn-realaudio',
    '.rake'    : 'text/x-script.ruby',
    '.ram'     : 'audio/x-pn-realaudio',
    '.rar'     : 'application/x-rar-compressed',
    '.rb'      : 'text/x-script.ruby',
    '.rdf'     : 'application/rdf+xml',
    '.roff'    : 'text/troff',
    '.rpm'     : 'application/x-redhat-package-manager',
    '.rss'     : 'application/rss+xml',
    '.rtf'     : 'application/rtf',
    '.ru'      : 'text/x-script.ruby',
    '.s'       : 'text/x-asm',
    '.sgm'     : 'text/sgml',
    '.sgml'    : 'text/sgml',
    '.sh'      : 'application/x-sh',
    '.sig'     : 'application/pgp-signature',
    '.snd'     : 'audio/basic',
    '.so'      : 'application/octet-stream',
    '.svg'     : 'image/svg+xml',
    '.svgz'    : 'image/svg+xml',
    '.swf'     : 'application/x-shockwave-flash',
    '.t'       : 'text/troff',
    '.tar'     : 'application/x-tar',
    '.tbz'     : 'application/x-bzip-compressed-tar',
    '.tci'     : 'application/x-topcloud',
    '.tcl'     : 'application/x-tcl',
    '.tex'     : 'application/x-tex',
    '.texi'    : 'application/x-texinfo',
    '.texinfo' : 'application/x-texinfo',
    '.text'    : 'text/plain',
    '.tif'     : 'image/tiff',
    '.tiff'    : 'image/tiff',
    '.torrent' : 'application/x-bittorrent',
    '.tr'      : 'text/troff',
    '.ttf'     : 'application/x-font-ttf',
    '.txt'     : 'text/plain',
    '.vcf'     : 'text/x-vcard',
    '.vcs'     : 'text/x-vcalendar',
    '.vrml'    : 'model/vrml',
    '.war'     : 'application/java-archive',
    '.wav'     : 'audio/x-wav',
    '.wma'     : 'audio/x-ms-wma',
    '.wmv'     : 'video/x-ms-wmv',
    '.wmx'     : 'video/x-ms-wmx',
    '.wrl'     : 'model/vrml',
    '.wsdl'    : 'application/wsdl+xml',
    '.xbm'     : 'image/x-xbitmap',
    '.xhtml'   : 'application/xhtml+xml',
    '.xls'     : 'application/vnd.ms-excel',
    '.xml'     : 'application/xml',
    '.xpm'     : 'image/x-xpixmap',
    '.xsl'     : 'application/xml',
    '.xslt'    : 'application/xslt+xml',
    '.yaml'    : 'text/yaml',
    '.yml'     : 'text/yaml',
    '.zip'     : 'application/zip'
}

exports.get = function(extension) {
	if (!extension) return 'text/plain';
	if (extension.indexOf('.') == -1) extension = '.' + extension;
	if (!types[extension]) return null;
	return types[extension];
}

server.js

var http = require('http'),
  path = require('path'),
  url  = require('url'),
  fs   = require('fs'),
  mime = require('./mime')

function error(code, res) {
  res.writeHead(code)
  res.end()
}

function output(file, res) {
  fs.readFile(file, 'binary', function(err, data) {
    if (err) {
        error(500)
        return
    }
    res.writeHead(200, {
        'Content-Type': mime.get(path.extname(file))
    })
    res.end(data, 'binary')
  })
}

var server = http.createServer(function(req, res) {
  if (req.method != 'GET') {
      error(405)
      return
  }
  var uri = url.parse(req.url)
  var file = path.join(process.cwd(), 'static', uri.pathname)
  path.exists(file, function(exists) {
    if (!exists) {
        error(404)
        return
    }
    fs.stat(file, function(err, stats) {
        if (err) {
            error(500)
            return
        }
        if (!stats.isDirectory() && !stats.isFile()) {
            error(404)
            return
        }
        if (stats.isDirectory()) {
            fs.readdir(file, function(err, files) {
                if (err) {
                    error(500)
                    return
                }
                if (!~files.indexOf('index.html')) {
                    error(403)
                    return
                }
                file = path.join(file, 'index.html')
                output(file, res)
            })
        } else output(file, res)
    })
  })
})

server.listen(80)