Save bandwidth using .htaccess
If you pay for your bandwidth, this wee line could save you hard cash..
save me hard cash! and help the internet!<ifModule mod_php4.c>
php_value zlib.output_compression 16386
</ifModule>
All it does is enables PHP’s built-in transparent zlib compression. This will half your bandwidth usage in one stroke, more than that, in fact. Of course it only works with data being output by the PHP module, but if you design your pages with this in mind, you can use php echo statements, or better yet, php “includes” for your plain html output and just compress everything! Remember, if you run phpsuexec, you’ll need to put php directives in a local php.ini file, not .htaccess.
Parmendra's PHP Blog 