# make pretty-print-build-depends-list
# make search key=dvd | more
# make search name=netscape | more
# pkg_info -xc lynx
# pkg_info -xD messagewall

Add this to your /etc/make.conf file:

.if ${.CURDIR:M*/usr/ports*}
.include "/etc/ports.conf"
.endif

Then for every port you want to customize a block like the following one in /etc/ports.conf:

.if ${.CURDIR:M*/www/apache*}
WITH_OPENSSL_BASE=1
APACHE_BUFFERED_LOGS=1
.endif

This will effectively add -DWITH_OPENSSL_BASE -DAPACHE_BUFFERED_LOGS when make is called under the apache port dir - http://www.mtdev.com/2005/02/saving-freebsd-ports-make-flags/