Quite possibly the best VNC client there is! – Remoter VNC - Remote Desktop Review

Once you get used to it, Remoter works outstandingly well with OS X's built-in VNC server. It has different "modes" for the mouse cursor (move, drag, scroll, etc) and you can zoom in and out easily. I have found it works poorly with alternative VNC servers like RealVNC, but that may be more a problem with them, not Remoter.
Review by $1K Master on Remoter VNC - Remote Desktop.