I used to love to whip up Rexx scripts for getting applications to work together on my Amiga. Now that was a useful OS!
Haven't seen Rexx yet for the Zaurus, but, as someone pointed out, IBM released the source for object-Rexx, so it may be possible to get it to run on the Zaurus.
In the mean time, I've found that Perl can do pretty much everything that Rexx did, and there is a version of Perl that runs on the Z -- it's what I use when I need to knock out a quick-and-dirty program or batch script.