Hi,
  The docs at: http://docs.xfce.org/xfce/thunar/using- … _and_media could
do with explaining the % expansions for commands.  In particular looking at thunar-volman/tvm-run.c I found the %d and %m expansions that
give device file and mount point.

As an example, on the Cameras tab I now have
digikam --download-from %m

which works nicely.
(Hmm, does that need quoting to ensure that we don't hit an evil named camera like ;rm -rf /* ?)

Dave