Is there a way to rename an external hard drive?
The label is a property of the drive's filesystem itself - you need to modify that using GParted or other tools. Here are some instructions in Ubuntu wiki:
Open the System > Administration menu and see if there's an entry for GParted (previously Partition Editor).
If there is, launch it. If there isn't, install the "gparted" package and it should now appear in the menu. Enter your password when prompted.
Disk drives are divided up into partitions. To find the partition you want to re-label, you first have to find the disk drive that contains it, using the drop-down menu in the upper right. It will show a device name like /dev/sdb and the drive's total size in parentheses. After selecting a drive, you will see a list of all partitions on that drive.
If the partition is mounted (has a key icon next to it), right-click on the partition and select Unmount.
With the key icon gone, right-click on the partition and select Label. If you can't select it, install the ntfsprogs package.
Enter the new partition name and press Ok.
The label change is now pending, but has not been completed. Press the Apply button near the top of the window. After confirming, it should say "All operations successfully completed". The drive now has a new label.
The "Disk Utility" tool that ships with most Ubuntu installations lets you change volume labels quite easily.
As with any disk operation, I would recommend performing a backup of the device first :-)
There is a duplicated question, see more here
With Ubuntu 13.04 search for Disks. Select the disk. Below the Volumes box, click the square button to unmount the disk. The square will change to triangle (Mount). Then click the More Options button and select Edit Filesystem Label... Edit the name, select Change and then mount the drive by clicking the Mount button.
Not as easy as Windows, but manageable