anyone know the best way to open a .ged file?

A quick Google search found http://fileinfo.com/extension/ged and the list of apps available for the various OS’s. Choose one that works with the version of OS X you have installed.

Then either purchase it (if necessary) and open the file.

http://pc.net/extensions/file/ged

Any text editor can open the file but the format of the data inside will not be easily understood. To see the info as it was designed to be viewed you'll need a family tree application of which the two most prominent are Mac Family Tree and Reunion. I think both have demo versions that will let

Reunion has a demo mode that is limited to 50 persons and some other restrictions. The Mac Family Tree is fully functional but can't save or print. I suggest you download and try both as they both have different user interfaces and methods of displaying the data.