USB drive not mounted in Virtualbox guest

Problem
I have a Linux host with a Windows 7 guest in Virtualbox. I want to transfer some big files to the Windows guest via a USB stick but the Windows guest doesn’t see the attached USB stick. What to do?

Solution
I didn’t find a proper solution but I have a workaround. In Virtualbox, before booting up the guest system, you can specify a CD/DVD image under Settings -> Storage (see this figure). This image will be mounted and will be visible in the guest.

So, collect the stuff you want to transfer in a directory, convert the folder to ISO image format and mount this image file before booting up the Windows guest. Works for me :)

Another solution is to set up a shared folder but I haven’t figured out yet how to do that.