~$ dpkg-query -W -f='${Priority} \t${Package} \n' | egrep -i 'standard|important|required' | sort
important adduser
important apt
important aptitude
important apt-utils
important bsdmainutils
important cpio
important cron
important debconf
important debconf-i18n
important debian-archive-keyring
important dhcp-client
important dmidecode
important ed
important gnupg
important gpgv
important groff-base
important ifupdown
important info
important iptables
important iputils-ping
important klogd
important laptop-detect
important libbz2-1.0
important libcwidget3
important libgcrypt11
important libgdbm3
important libgnutls11
important libgnutls13
important libgnutls26
important libgpg-error0
important libldap2
important libldap-2.2-7
important liblzo1
important liblzo2-2
important libncursesw5
important libnewt0.52
important libopencdk10
important libopencdk8
important libpcre3
important libpopt0
important libreadline5
important libsasl2
important libsasl2-2
important libssl0.9.8
important libsysfs2
important libtasn1-0
important libtasn1-2
important libtasn1-3
important libusb-0.1-4
important libvolume-id0
important libwrap0
important logrotate
important man-db
important manpages
important module-init-tools
important modutils
important nano
important netbase
important netcat
important net-tools
important nvi
important sysklogd
important tasksel
important tasksel-data
important tcpd
important traceroute
important udev
important vim-common
important wget
important whiptail
required base-files
required base-passwd
required bash
required bsdutils
required coreutils
required debianutils
required diff
required dpkg
required dselect
required e2fslibs
required e2fsprogs
required findutils
required gcc-4.1-base
required gcc-4.2-base
required gcc-4.3-base
required grep
required gzip
required hostname
required initscripts
required libacl1
required libattr1
required libblkid1
required libc6
required libcap1
required libcomerr2
required libdevmapper1.02
required libdevmapper1.02.1
required libgcc1
required liblocale-gettext-perl
required libncurses5
required libpam0g
required libpam-modules
required libpam-runtime
required libselinux1
required libsepol1
required libslang2
required libss2
required libstdc++6
required libtext-charwidth-perl
required libtext-iconv-perl
required libtext-wrapi18n-perl
required libuuid1
required login
required lsb-base
required makedev
required mawk
required mktemp
required mount
required ncurses-base
required ncurses-bin
required passwd
required perl-base
required procps
required sed
required slang1a-utf8
required sysvinit
required sysvinit-utils
required sysv-rc
required tar
required tzdata
required util-linux
required zlib1g
standard at
standard bc
standard bin86
standard bind9-host
standard bison
standard dc
standard dictionaries-common
standard dnsutils
standard doc-debian
standard doc-linux-text
standard exim4
standard exim4-base
standard exim4-config
standard exim4-daemon-light
standard file
standard finger
standard flex
standard ftp
standard gettext-base
standard gnu-efi
standard iamerican
standard ibritish
standard less
standard libbind9-30
standard libc6-amd64
standard libdb4.2
standard libdb4.3
standard libdb4.4
standard libdb4.5
standard libdb4.6
standard libdns16
standard libdns32
standard libevent1
standard libgc1
standard libgc1c2
standard libgpmg1
standard libgssapi2
standard libident
standard libidn11
standard libisc32
standard libisc7
standard libkrb53
standard liblockfile1
standard liblwres1
standard liblwres30
standard libmagic1
standard libnewt0.51
standard libnfsidmap1
standard libnfsidmap2
standard libnss-db
standard libreadline4
standard librpcsecgss3
standard libssp0
standard libtextwrap1
standard locales
standard lpr
standard lsof
standard m4
standard mailx
standard make
standard mime-support
standard mpack
standard mtools
standard mtr-tiny
standard mutt
standard ncurses-term
standard nfs-common
standard openbsd-inetd
standard openssh-client
standard patch
standard pciutils
standard perl
standard perl-modules
standard pidentd
standard portmap
standard procmail
standard python
standard python2.3
standard python-central
standard python-minimal
standard python-support
standard readline-common
standard reportbug
standard sharutils
standard slang1
standard strace
standard tcsh
standard telnet
standard texinfo
standard time
standard update-inetd
standard w3m
standard wamerican
standard whois