This is actually a placeholder for me actually. Bookmarks get lost but blog posts don't... At least not so easily. Visit the url https://help.ubuntu.com/community/Tasksel. As it is written in the Documentation Page
"Tasksel is a Debian/Ubuntu tool that installs multiple related packages as a co-ordinated "task" onto your system.This function is similar to that of meta-packages, and, in fact, most of the tasks available from tasksel are also available as meta-packages from the Ubuntu package managers (such as Synaptic Package Manager or KPackageKit)".
In my case, I wanted to clean my Ubuntu server from the Gnome desktop I had installed but, in the process, some other needed packages were gone away too. I then found Tasksel, selected the installation I wanted and just installed. It's not like Synaptic or Aptitude. You don't choose the packages you want. Your choose distributions. Not packages. For example with Synaptic you would choose to install apache2, php5, mysql5-server etc. With Tasksel you choose "Basic Ubuntu Server" and "LAMP-server" and install. That's all!