List packages by size

I need that quite often, but keep forgetting the exact syntax (except for Debian, where it's really simple). 😉

RPM-based (Redhat, Fedora, Mandriva, Suse ...)

rpm -qa --queryformat '%{SIZE} %{NAME}\n' | sort -nr | head -20

DPKG-based (Debian, Ubuntu, Sidux ...)

wajig size  | sort -k 2 -nr | head -20

Pacman-based (Arch, DeLi, Chakra)

pacman -Qi | awk '/^Installed Size/{print int($4), name} /^Name/{name=$3}' \
| sort -nr | head -20