If you'e recently installed Inkscape on a Mac, you might be wondering where all the darn fonts are. In order to fix this problem, you will need to recompile Inkscape from source... Just kidding! It’s actually a very simple fix.
Basically, Inkscape (on Macs) likes fonts to be in /Library/Fonts. There might be other places where Inkscape looks for fonts. This is just what worked for me on a computer running 10.9 Mavericks.
See also: How to draw a flat, single color lightbulb icon in Inkscape
/Library/Fonts is typically hidden and probably for good reason. Please be very careful not to change any other files inside this directory. Doing so could cause your computer to stop working.
To get to the fonts directory, open up Finder and hit Command + Shift + G. When the dialog appears, type /Library/Fonts and hit enter. Voila! Copy whatever fonts you want Inkscape to find into this folder. Inkscape will need to be restarted to actually find the fonts.
Alternatively, you can access this dialog using the menu in Finder. Select Go then select Go to Folder from the drop down.
Inkscape should have no problem finding fonts in /Library/Fonts. If you are still having problems, consider checking that there isn’t something wrong with the font file itself. To the best of my knowledge, a recent version of Inkscape should do just fine with TrueType, OpenType, and Type1 fonts.
OS X 10.10 Yosemite and Inkscape 0.91
Inkscape 0.91 running on OS X 10.10 Yosemite seems to do just fine with fonts installed using the built in Font Book. Simply double click on the font file and click Install Font in the Font Book window that should pop open. No need to manually copy the files.