Gparted stands for Gnome Partition Editor.
This tool has GUI interface and it is really easy to manage your partitions with it.
It also comes as GPartEd live CD.
I think the live CD is a must-have tool for any Linux administrator.
Gparted can not operate on mounted Partition, that is why the Live CD is more important.
Debian / Ubuntu
sudo apt-get install gparted
You can see on this screenshot, all its features, you can get this, by going to the main menu and clicking on:
To work with a particular partition click on it to highlight it and then if it is not mounted you can.
All this options are under Partition menu.
On View->Device Information, you will enable the view of the information about the Disk you are watching