Use 'ar t' to get a listing of the contents:
[rw@fever]/tmp $ar t xterm_222-1etch2_i386.deb
debian-binary
control.tar.gz
data.tar.gz
and 'ar x' to extract the components:
[rw@fever]/tmp $ar x xterm_222-1etch2_i386.deb data.tar.gz
[rw@fever]/tmp $tar tzf data.tar.gz
../
../usr/
../usr/bin/
../usr/bin/koi8rxterm
../usr/bin/lxterm
../usr/bin/resize
../usr/bin/uxterm
很给力吧