dpkg query - where you are interested in size or want to sort by size - read dpkg-query manpage for explanation of switches

dpkg-query

#!/bin/dash
# (c) 2011 Gary Wright - now released into public domain.
dpkg-query -W --showformat='${Installed-Size;-10}\t${Section;-15}\t${Package;-30}\n' | sort -g

dpkg-query -W --showformat='${Installed-Size;-10}\t${Section}\t${Package}\n' | sort -g
dpkg-query --showformat='${Installed-Size;-10} ${Package}\n' -W | sort -g
dpkg-query --showformat='${Package}\n${Description}' -W macaulay*

#dpkg-query --showformat='${Installed-Size;-10} ${Package}\n' -W lib* | sort -g

dpkg-query --showformat='${Status;-2} ${Installed-Size;-10} ${Package;-20} ${Version}\n' -W "python2.5*" | \
egrep '^in' | cut -c4- | sort -g

This example is useful for Ubuntu if you want to identify unofficial or multiverse packages:
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dpkg-query -W --showformat='${Installed-Size;-10}\t${Section;-15}\t${Package;-30}\t${Maintainer}\n' | \
sed 's/\<.*\>$//' | grep -v -w Ubuntu | grep -v -w Xubuntu | grep -v metapackages | \
wc -l >> /tmp/dpkgLnotWordUbuntuOrXubuntu.out