What's a good terminal manager for OS X?
Taken in mind that setting up a tunnel by your self is really easy, you may consider using iTerm2 as a replacement to Terminal.app.

iTerm2 features profiles, so you may connect to any SSH server instantly.

Advantages over Terminal.app:

http://www.iterm2.com/

If you still need to use a gui for tunneling, then you may use an app like: 

SSHTunnel or SSH Tunnel Manager