Working out how to use OS X system fonts in X11 applications is a nuisance. Took me ages to find out (again) how to do this. This time I’m making a note of how to do it.
mkdir .fonts/sys
ln -s /System/Library/Fonts ~/.fonts/sys
mkdir .fonts/lib
ln -s /Library/Fonts ~/.fonts/lib
mkdir .fonts/user
ln -s ~/Library/Fonts ~/.fonts/user
I have fonts in both /System/Library and /Library. Anyway, fire up the Gimp and it should allow access to all your OS X fonts in the text tool.
[thanks for this page which built on this]