/media/sf_Vboxshare

sudo adduser $USER vboxsf

sudo mount -t vboxsf <share-name> /where/to/share

sudo add-apt-repository ppa:george-edison55/nitroshare
sudo apt-get update
sudo apt-get install nitroshare

virtualbox-4.3_4.3.6-91406~Ubuntu~precise_amd64 with extenstion pack -
Oracle_VM_VirtualBox_Extension_Pack-4.3.6-91406

mount -t vboxsf  /shared-name /where/to/share

sudo mount -t vboxsf /home/myshare /mnt