http://wordpress.org/extend/plugins/peters-login-redirect/
is an excellent plugin for that
or, depending on how you’re doing your login you can code it…
//ADD LOGIN LINK TO MENU
add_filter('wp_nav_menu_items', 'add_login_logout_link', 10, 2);
function add_login_logout_link($items, $args) {
$voodooredir = htmlspecialchars($_SERVER['REQUEST_URI']);
$loginoutlink = wp_loginout($voodooredir, false);
$items .= '<li>'. $loginoutlink .'</li>';
return $items;
}
I use this to put a login in my menu, which redirects to whatever page the user logged in from
I second that – the Peter’s Login Redirect plugin is what I’ve used in the past, and works extremely well – very flexible and easy to use!
If you just want to build a login url that redirects to a specific page after successful login:
http://codex.wordpress.org/Function_Reference/wp_login_url
Or if you want to play with action hooks on login:
http://codex.wordpress.org/Plugin_API/Action_Reference/wp_login