Using "pmount" to mount removable storage works great. Any user can run pmount /dev/sdaX, and it will be mounted appropriately under /media/sdaX.
USB external disk problem
... but I found a problem with a external USB disk. This is an internal SATA disk, with a hard drive SATA->USB case to put it in. It can't mount it using this. These are my notes about this:
http://lists.freedesktop.org/archives/hal/2005-October/thread.html#3440 (first message). My exact problem
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=314985 Debian bug report.
Apparrantly sysfsutils 1.3 would fix this, but it isn't avalable for sarge. But sysfsutils isn't even installed right now. It is interesting that this same drive does work on my laptop, which is i386 instead amd64, and neither of them has sysfsutils installed.
There are other options I am investigating.