prepare:
http://wvarner.blogspot.com/2008/05/installing-virtualbox-guest-additions.html


sudo mkdir /mnt/my_folder
sudo nano /etc/rc.local

Add line:

mount -t vboxsf -w -o uid=1000,gid=1000 my_shared_folder_name /mnt/my_folder

Save, quit. Reboot:

sudo reboot


Read more: http://feeds.dzone.com/~r/dzone/snippets/~3/23fpYouXL0M/12621