[CentOS] umount'ing a /media/disk... as a user

Hello!

Currently, whenever I attempt to umount /media/disk (or -1, etc), I 
either have to be user or have to have given the account sudo 
privileges.  Since these "disks" are usually just flash-memory sticks, 
I'd really rather have the permission to umount them be given to users.  
The /etc/mtab shows the /media filesystems, /etc/fstab does not.

Thank you,
Charles Campbell