http://htaccess.wordpress.com/2008/07/16/sending-correct-content-type-headers-with-htaccess/

Learn how to set up your mime headers in .htaccess here.

Sample .htaccess file from Mozilla

The developers at Mozilla explain how the purpose of configuring the Apache web server to send many common file types with the correct MIME types

Provided .htaccess file

# CSS

AddType text/css .css

# XHTML

AddType application/xhtml+xml .xhtml

# XML

AddType text/xml .xml

# SVG

AddType image/svg+xml .svg .svgz

AddEncoding x-gzip .svgz

# HTML

# Server Side Includes (SSI)

AddType text/html .shtml

# Active Server Pages

AddType text/html .asp

# Favicons

AddType image/vnd.microsoft.icon .ico

# Macromedia

AddType application/x-shockwave-flash .swf

AddType application/x-director .dir .dcr .dxr .fgd

AddType application/x-authorware-map .aam

AddType application/x-authorware-seg .aas

AddType application/x-authorware-bin .aab

AddType image/x-freehand .fh4 .fh5 .fh7 .fhc .fh

# Adobe PDF

AddType application/pdf .pdf

# Real

AddType application/vnd.rn-realmedia .rm

AddType audio/vnd.rn-realaudio .ra .ram

AddType video/vnd.rn-realvideo .rv

AddType audio/x-pn-realaudio-plugin .rpm

# Microsoft multimedia

AddType video/x-ms-asf .asf .asx

AddType audio/x-ms-wma .wma

AddType audio/x-ms-wax .wax

AddType video/x-ms-wmv .wmv

AddType video/x-ms-wvx .wvx

AddType video/x-ms-wm .wm

AddType video/x-ms-wmx .wmx

AddType application/x-ms-wmz .wmz

AddType application/x-ms-wmd .wmd

# MPEG

AddType audio/x-mpegurl .m3u

# Binary Compressed files and archives

AddType application/zip .zip

AddType application/x-gzip .gz

AddType application/x-gtar .gtar

AddType application/x-rar-compressed .rar

AddType application/octet-stream .dmg

# Java

AddType application/x-java-applet .class

# Quicktime movies

AddType video/quicktime .mov .qt

# XBM files

AddType image/x-xbitmap .xbm

# WAV files

AddType audio/x-wav .wav

# Bittorrent

AddType application/x-bittorrent .torrent

Common file extensions

that are good to know, organized by file format..doc Microsoft Word Document

.log Log File

.msg Mail Message

.rtf Rich Text Format File

.txt Text File

.wpd WordPerfect Document

.wps Microsoft Works Word Processor Document

.123 Lotus 1-2-3 Spreadsheet

.csv Comma Separated Values File

.dat Data File

.db Database File

.dll Dynamic Link Library

.mdb Microsoft Access Database

.pps PowerPoint Slide Show

.ppt PowerPoint Presentation

.sql Structured Query Language Data

.wks Microsoft Works Spreadsheet

.xls Microsoft Excel Spreadsheet

.xml XML File