RE dubious's comment: "Being able to read gzip streams from ftp and http is near the top of my personal wishlist at the moment..."
One way to read a gzip stream over http is to daisychain stream wrappers, e.g.:
<?
$fp = fopen("compress.zlib://http://some.website.org/example.gz", "r");
?>