There REALLY should be a system in place similar to how HTS currently works (you login at whatever page on HTS.org, and it brings you back to that page logged in). Instead of just sending them to /?need_login, do something like... /?need_login&redir=(URL encoding for where on the forums they were trying to go). That way, when a user clicks on a forums link, all they need to do is login, and boom, they're right where they were trying to go to. It should be relatively easy to implement since HTS does it already for existing pages.
~ Kage ~