You can install the default Ubuntu desktop by executing the following:
sudo apt-get install ubuntu-desktop
There are many desktop alternatives which you may install and use, like:
sudo apt-get install gnome-shell
转自： http://askubuntu.com/questions/53822/how-do-you-run-ubuntu-server-with-a-gui
ubuntu14.04 server安装gnome-desktop
原文：http://www.cnblogs.com/pinganzi/p/5899800.html