How Do I Expand A Virtual Box Drive?

I just wanted to give a quick thanks to Seppe vanden Broucke whose blog post on how to expand a virtual drive saved me a whole bunch of time.  When I do Java development I typically use a virtual machine to host the environment.  I find it useful because you can quickly replicate/archive the environment.  I set up a Xubuntu environment that ran out of disk space and caused all sorts of trouble for me.  Thanks to Seppe I was up an running within an hour with a newly expanded virtual drive.