As more and more kernel updates get installed on your system the grub menu tends to grow longer. This is easy to fix:
Back up your grub menu file:
sudo cp /boot/grub/menu.lst /boot/grub/menu.lst.bak
Edit your menu file:
sudo gedit /boot/grub/menu.lst
Comment out any unwanted entries by adding a # in the beginning of each line that should not be displayed.
Save the file, and when you reboot the grub menu should be nice and small again.