This is a list of the types, and their associated extensions. If you want to change any of these items, you can place the new information in your .htaccess file.
# application/activemessage application/andrew-inset application/applefile application/atomicmail application/dca-rft application/dec-dx application/mac-binhex40 application/macwriteii application/msword application/news-message-id application/news-transmission application/octet-stream bin application/oda oda application/pdf pdf application/postscript ai eps ps application/remote-printing application/rtf rtf application/slate application/x-mif mif application/wita application/wordperfect5.1 application/x-csh csh application/x-dvi dvi application/x-hdf hdf application/x-latex latex application/x-netcdf nc cdf application/x-sh sh application/x-tcl tcl application/x-tex tex application/x-texinfo texinfo texi application/x-troff t tr roff application/x-troff-man man application/x-troff-me me application/x-troff-ms ms application/x-wais-source src application/zip zip application/x-bcpio bcpio application/x-cpio cpio application/x-gtar gtar application/x-shar shar application/x-sv4cpio sv4cpio application/x-sv4crc sv4crc application/x-tar tar application/x-ustar ustar audio/basic au snd audio/x-aiff aif aiff aifc audio/x-wav wav image/gif gif image/ief ief image/jpeg jpeg jpg jpe image/tiff tiff tif image/x-cmu-raster ras image/x-portable-anymap pnm image/x-portable-bitmap pbm image/x-portable-graymap pgm image/x-portable-pixmap ppm image/x-rgb rgb image/x-xbitmap xbm image/x-xpixmap xpm image/x-xwindowdump xwd message/external-body message/news message/partial message/rfc822 multipart/alternative multipart/appledouble multipart/digest multipart/mixed multipart/parallel text/html html htm tml text/plain txt text/richtext rtx text/tab-separated-values tsv text/x-setext etx video/mpeg mpeg mpg mpe video/quicktime qt mov video/x-msvideo avi video/x-sgi-movie movie