Add an entry to /etc/fstab. Here is an entry that I added just a few hours ago for my Seagate USB drive:
UUID=4ACC734ECC733375 /media/Linux ext3 errors=remount-ro,defaults,users,noatime,nodiratime 0 0
The key here is the "users" entry that allows users to mount and unmount the drive.
Edit: this works for specific drives - I don't know if it can be enabled for all drives with one entry.