If you recently upgraded to Mac OS X 10.10 Yosemite, you may find that your virtual hosts are now giving you "403 Forbidden" errors. To fix this, add the following line to each of your virtual host's Directory Custom Directives
Require all granted
Once you've added that line, click "Apply Changes" and restart Apache.
Please note: That line needs to be added to your Directory custom directives. Not your VirtualHost directives.