list of installed packages
cat /var/lib/dpkg/status | grep Package: | awk -F: '{print $2}' | sort
assuming you have grep, Gawk and sort installed...
by the way, this is mine :
root# cat /var/lib/dpkg/status | grep Package: | awk -F: '{print $2}' | sort
adv-cmds
apr
apr-lib
apr-util
apt
apt7
apt7-key
apt7-lib
apt7-ssl
backgrounder
base
bash
basic-cmds
berkeleydb
bigboss
bitesms
bootstrap-cmds
bzip2
classpath
com.bigboss.airplane.bossprefs
com.bigboss.aptbackup
com.bigboss.bossprefs
com.bigboss.categories
com.bigboss.categoriesicons1
com.bigboss.safari.bossprefs
com.clezz.dock
com.efiko.tonefxs
com.ericasadun.utilities
com.iappdev.ireboot
com.iphonemodem
com.jpifher.lighttpdswitchbossprefs
com.microseconds.moonphase
com.misurda.filedownload.plugin
com.saurik.iphone.ske
com.sosiphone.iphonedelivery
com.tidalpoolsoftware.tether
com.whomer.sbstoggleveency
com.zataang.logmailer
coreutils
coreutils-bin
curl
cycorder
cydia
cydia-sources
darwintools
developer-cmds
diffutils
diskdev-cmds
dpkg
essential
eu.heinelt.ifile
expat
file-cmds
findutils
firmware
gawk
gcrypt
gettext
gnupg
grep
gzip
inetutils
iphone-java
ispazio.net
jamvm
javasqlite
jocstrap
jp.ashikase.categoriessb
less
libffi
libgpg-error
libhide
libpcap
libvncserver
libxml2
libxml2-lib
lighttpd
lsof
lynx
lzma
mdnsresponder
mobilesubstrate
mobileterminal
modmyifone
nail
nano
ncurses
netatalk
network-cmds
nmap
openssh
openssl
p7zip
pam
pam-modules
patch
pcre
php
preferenceloader
profile.d
readline
rhino
rsync
saurik
sbsettings
sbsettingstoggles
sed
shell-cmds
sosiphone.com
sqlite3
sqlite3-lib
ste
sudo
syslogd
system-cmds
tar
top
uicaboodle
uikittools
unrar
unzip
veency
vim
vsftpd
wget
whois
xml2
zip
zodttd