How can I give other drives and partitions short, meaningful names in nautilus?

Open disk-utility from your Unity dash and click at your Harddisk .then click at the partition where you want a label then click Edit File System Label and give your New Label .

Partition labelling is possible using the GParted tool. You just select the partition you want to change the label to, right click and choose the label option. However, you can't change the label for mounted partitions, so you are out of luck for your system partitions.