Default Usage
Get the meta for all keys:
<?php $meta = get_post_meta($post_id); ?>
Get the meta for a single key:
<?php $key_1_values = get_post_meta( 76, 'key_1' ); ?>
for example:
$myvals = get_post_meta($post_id);
foreach($myvals as $key=>$val)
{
echo $key . ' : ' . $val[0] . '<br/>';
}
Note: some unwanted meta keys starting with "underscore(_)" will also come, so you will need to filter them out.
For reference: See Codex