Simple interface for users who want to configure their system to perform a specific task (ie. mailserver, LAMP)
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).