During ubuntu boot phase, a beatiful Logo appear on screen, indicate you are soon starting your desktop. What about changing this default screen ? Yes all is possible on Ubuntu and mainly on Linux ;)

OK, first, try to install a new plymouth theme in the proposed list.

frederic@nostromo64:~$ aptitude search plymouth-theme
v   plymouth-theme                    -
i   plymouth-theme-fade-in            - graphical boot animation and logger - fade-in theme
i   plymouth-theme-glow               - graphical boot animation and logger - glow theme
p   plymouth-theme-kubuntu-logo       - graphical boot animation and logger - kubuntu-logo theme
p   plymouth-theme-kubuntu-text       - graphical boot animation and logger - kubuntu-text theme
p   plymouth-theme-lubuntu-logo       - plymouth theme for Lubuntu
p   plymouth-theme-sabily             - plymouth theme for Sabily
p   plymouth-theme-script             - graphical boot animation and logger - script theme
i   plymouth-theme-solar              - graphical boot animation and logger - solar theme
p   plymouth-theme-spinfinity         - graphical boot animation and logger - spinfinity theme
p   plymouth-theme-text               - graphical boot animation and logger - text theme
i   plymouth-theme-ubuntu-logo        - graphical boot animation and logger - ubuntu-logo theme
i   plymouth-theme-ubuntu-text        - graphical boot animation and logger - ubuntu-logo theme
p   plymouth-theme-ubuntustudio       - Ubuntu Studio Plymouth theme
p   plymouth-theme-xubuntu-logo       - graphical boot animation and logger - xubuntu-logo theme
p   xubuntu-plymouth-theme            - Plymouth theme for Xubuntu

Then, select the one you want and execute the following command lines:

frederic@nostromo64:~$ sudo update-alternatives --config default.plymouth

Select in proposed list one of the theme installed :

frederic@nostromo64:~$ sudo update-alternatives --config default.plymouth

There are 4 choices for the alternative default.plymouth (providing/lib/plymouth/themes/default.plymouth).

Sélection   Chemin                                                 Priorité  État
------------------------------------------------------------
* 0            /lib/plymouth/themes/ubuntu-logo/ubuntu-logo.plymouth   100       mode automatique
  1            /lib/plymouth/themes/fade-in/fade-in.plymouth           10        mode manuel
  2            /lib/plymouth/themes/glow/glow.plymouth                 10        mode manuel
  3            /lib/plymouth/themes/solar/solar.plymouth               10        mode manuel
  4            /lib/plymouth/themes/ubuntu-logo/ubuntu-logo.plymouth   100       mode manuel
Appuyez sur  pour conserver la valeur par défaut[*] ou choisissez le numéro sélectionné :

And install this theme on boot sequence

frederic@nostromo64:~$ sudo sudo update-initramfs -u

You can verify it with the command line

sudo plymouthd ; sudo plymouth --show-splash ; sleep 10 ; sudo plymouth --quit

And then, reboot and enjoy !

(sorry for french screenshot... I run a french installation of Ubuntu ;)