I had written a tutorial about how to add splash image for grub 2.Today I found couple of Grub2 splash image and they are very easy to add into your grub because the deb packages provided.

Download link:

http://gnome-look.org/content/show.php/Grub2+Splash+Image+?content=125657

Choose one image and download the package,then just double click to install and finally reboot.
If it doesn’t work,try to install in command line:

sudo dpkg -i package_name_here

And for amd64 machine,try following to install those packages for i386:

sudo dpkg -i --force-architecture filename.deb

Screenshots: