If we consider common available technology and the average use of a FreeBSD installation as desktop or server then I think these are sensible defaults for /etc/src.conf under FreeBSD 7.

WITHOUT_ATM=yes

How many of you run ATM to your FreeBSD box?

WITHOUT_BIND_DNSSEC=yes
WITHOUT_BIND_ETC=yes
WITH_BIND_LIBS=yes
WITHOUT_BIND_MTREE=yes
WITHOUT_BIND_NAMED=yes

Do you really need a full installation of BIND on your machine? In most cases you simply need a caching, recursive resolver. For this just install unbound (found in ports/dns/unbound). Do note that I did not specify WITHOUT_BIND_UTILS so tools like dig and nslookup will still be installed. Only if you need an authoratative nameserver might you want BIND. On the other hand, you might prefer to install NSD (ports/dns/nsd).

WITHOUT_BLUETOOTH=yes

Most systems will probably not use Bluetooth at all.

WITHOUT_I4B=yes

Do you even use ISDN?

WITHOUT_IPFILTER=yes

Most people I know use either ipfw or pf, so little need for ipf.

WITHOUT_IPX=yes

You seriously still use IPX? Even NetWare is IP-native nowadays.

WITHOUT_NIS=yes

I would hope most systems are using some sort of LDAP lookup nowadays. NIS seriously doesn't scale.

WITHOUT_SENDMAIL=yes

Given the ease of configuring Postfix, why would one want to bother with the archaic syntax of Sendmail? It has served faithfully for many, many years, but its design and configuration are archaic.