Retrieving list of Custom Post Types

There’s a core function for that: get_post_types():

<?php get_post_types( $args, $output, $operator ); ?>

So, for example, to return public, custom post types by name:

$custom_post_types = get_post_types( array(
    // Set to FALSE to return only custom post types
    '_builtin' => false,
    // Set to TRUE to return only public post types
    'public' => true
) );