From virtualenv, pip freeze > requirements.txt give TONES of garbage! How to trim it out?

I'm following this tutorial: http://devcenter.heroku.com/articles/django

At some point I'm suposed to do:

pip freeze > requirements.txt

(Ofc. from virtualenv created instance of python)

And I get this:

(venv)przemoli@ubuntu:~/Programowanie/hellodjango$ cat requirements.txt 
BeautifulSoup==3.2.0
Brlapi==0.5.5
CherryPy==3.1.2
ClientForm==0.2.10
Django==1.3
GnuPGInterface==0.3.2
PAM==0.4.2
PIL==1.1.7
Routes==1.12.3
Twisted-Core==11.0.0
Twisted-Names==11.0.0
Twisted-Web==11.0.0
WebOb==1.0.8
adium-theme-ubuntu==0.3.1
apt-xapian-index==0.44
apturl==0.5.1ubuntu1
chardet==2.0.1
command-not-found==0.2.44
configglue==1.0
cssutils==0.9.8a1
defer==1.0.2
distribute==0.6.19
django-tagging==0.3.1
dnspython==1.9.4
duplicity==0.6.15
gnome-app-install==0.4.7-nmu1ubuntu2
httplib2==0.7.2
jockey==0.9.4
keyring==0.6.2
launchpadlib==1.9.8
lazr.restfulclient==0.11.2
lazr.uri==1.0.2
louis==2.3.0
lxml==2.3
mechanize==0.1.11
nvidia-common==0.0.0
oauth==1.0.1
onboard==0.96.1
oneconf==0.2.6.7
papyon==0.5.5
pexpect==2.3
piston-mini-client==0.6
protobuf==2.4.0a
psycopg2==2.4.4
pyOpenSSL==0.12
pycrypto==2.3
pycups==1.9.59
pycurl==7.19.0
pyinotify==0.9.1
pyparsing==1.5.2
pyserial==2.5
pysmbc==1.0.10
python-apt==0.8.0ubuntu9
python-dateutil==1.4.1
python-debian==0.1.20ubuntu2
python-virtkey==0.60.0
pyxdg==0.19
sessioninstaller==0.0.0
simplejson==2.1.6
system-service==0.1.6
ubuntu-sso-client==1.4.0
ubuntuone-couch==0.3.0
ubuntuone-installer==2.0.0
ubuntuone-storage-protocol==2.0.0
ufw==0.30.1-2ubuntu1
unattended-upgrades==0.1
usb-creator==0.2.23
virtualenv==1.6.4
wadllib==1.2.0
wsgiref==0.1.2
xdiagnose==1.1
xkit==0.0.0
zope.interface==3.6.1

When deploying on heroku it fails at Brlapi .....

I see lots of stuff from my main python installation which is on ubuntu. Which is BAD since Ubuntu use python for quite a few thing itself (ubuntu-one, usb-creator, etc..).

I do not need them on heroku! I need only Django, psycopg2, and their dependencies. I do not even know if its fault of pip, or virutalenv. (If you want to know my setup look at link above I copied it into terminal)

That is one thing that has bugged me too quite a bit. This happens when you create a virtualenv without the --no-site-packages flag.

There are a couple of things you can do:

1. Create virtualenv with the --no-site-packages flag.
2. When installing apps, dont run pip install <name> directly, instead, add the library to your requirements.txt first, and then install the requirements. This is slower but makes sure your requirements are updated.
3. Manually delete libraries you dont need. A rule of thumb i follow for this is to add whatever is there in my INSTALLED_APPS, and database adapters. Most other required libraries will get installed automatically because of dependencies. I know its silly, but this is what I usually end up doing.

-- Edit --

I've since written a couple of scripts to help manage this. The first runs pip freeze and adds the found library to a provided requirements file, the other, runs pip install, and then adds it to the requirements file.

function pipa() {
    # Adds package to requirements file.
    # Usage: pipa <package> <path to requirements file>
    package_name=$1
    requirements_file=$2
    if [[ -z $requirements_file ]]
    then
        requirements_file='./requirements.txt'
    fi
    package_string=`pip freeze | grep -i $package_name`
    current_requirements=`cat $requirements_file`
    echo "$current_requirements\n$package_string" | LANG=C sort | uniq > $requirements_file
}

function pipia() {
    # Installs package and adds to requirements file.
    # Usage: pipia <package> <path to requirements file>
    package_name=$1
    requirements_file=$2
    if [[ -z $requirements_file ]]
    then
        requirements_file='./requirements.txt'
    fi
    pip install $package_name
    pipa $package_name $requirements_file
}