OSX implementation of WinBoard / XBoard? Is there a Mac OSX implementation (or equivalent) of WinBoard / XBoard?
You can technically still use XBoard, but you will need to install X11 from MacPorts, since IIRC Apple no longer ships it.
Julien Marcel has a collection of well-compiled OS X chess engines (which do not require emulation).
As for not having a ChessBase client, HIARCS Chess Explorer does fine.
(FWIW, there is a port of XBoard to Cocoa - currently named OSXBoard - but it seems to have stalled.)