Create archives by author role

You may be able to abuse add_rewrite_endpoint for this purpose, depending on exactly what you want to do.

Some examples:

// add an endpoint
// http:domain.com/role/
// http:domain.com/role/foo/ 
function wpa_add_role_endpoint(){
    add_rewrite_endpoint( 'role', EP_ALL );
}
add_action( 'init', 'wpa_add_role_endpoint' );


// check if a role parameter exists, like:
// http:domain.com/role/foo/
function wpa_role_query( $query ){
    if( $query->get('role') ){
        echo $query->get('role'); // echoes 'foo'
        // modify the query $query->set( 'somevar', 'someval' );
    }
}
add_action( 'pre_get_posts', 'wpa_role_query' );


// check if role is in query vars array, like:
// http:domain.com/role/
function wpa_role_parse( $query ){
    if( array_key_exists( 'role', $query->query_vars ) )
        die('role query');
}
add_action( 'parse_request', 'wpa_role_parse' );