In /etc/fstab:
/dev/sdb1 /media/usbdisk vfat utf8,user,noauto 0 0
I put in noauto because the filesystem will be mounted by root otherwise. I prefer to use the automounter (autofs) for this drive, so that it mounts as my group.
/etc/auto.master:
/misc /etc/auto.misc
/etc/auto.misc:
storage -fstype=vfat,user,uid=500,gid=500,utf8 :/dev/sdc1
Do a service autofs start and a chkconfig autofs on and you are ready to go. Make a link to /misc/storage on your desktop and then whenever you double-click on it, it will be mounted as uid 500, gid 500.