After installing Ubuntu :

Latex:
sudo apt-get install texlive texmaker
or
sudo apt-get install tetex-base tetex-bin tetex-extra

GCC:
sudo apt-get install build-essential

GFortran:
sudo apt-get install gfortran

G95:
Add following statements to /etc/apt/sources.list.
deb ftp://www.gfd-dennou.org/library/cc-env/Linux/debian-dennou stable/
deb-src ftp://www.gfd-dennou.org/library/cc-env/Linux/debian-dennou stable/

sudo apt-get update
sudo apt-get install g95

Acrobar Reader:
sudo apt-get install acroread mozilla-acroread acroread-plugins

LATEX:
sudo apt-get install texlive texmaker

Mplayer:
gedit /etc/apt/sources.list

enter these two lines and save your file

deb http://archive.ubuntu.com/ubuntu gutsy universe multiverse
deb-src http://archive.ubuntu.com/ubuntu gutsy universe multiverse

Now you need to run the following command to update the source list

sudo apt-get update

Install mplayer using the following command

sudo apt-get install mplayer

Installing libdvdcss2 and w32 video codecs in Ubuntu Gutsy Gibbon

sudo wget http://www.medibuntu.org/sources.list.d/gutsy.list -O /etc/apt/sources.list.d/medibuntu.list

wget -q http://packages.medibuntu.org/medibuntu-key.gpg -O- | sudo apt-key add -
sudo apt-get update
sudo apt-get install w32codecs libdvdcss2
sudo apt-get update
sudo apt-get install mozilla-mplayer

VLC:
sudo apt-get install vlc
#sudo apt-get --purge autoremove vlc

BANSHEE:
sudo apt-get install banshee
#sudo apt-get --purge autoremove banshee

MISC:
sudo apt-get install emacs grace xfig xpdf gv
sudo apt-get install nautilus-open-terminal