I haven't used Xee very long, but already found it much better than any other image viewer tried. But I have a wish for a feature:

I think it wouldn't make sence to demand lots of new sophisticated features only few are going to use, but almost everybody needs. The trouble is of course that everybody needs different features.

I have suggestion for a solution: Make Copy/Move destination list command also work with scripts and applications, not just foulders. Then it would be easy to launch them with the current image as argument.
(Allowing them to be dragged there would be nice as well, but for start, editing plist is easy enough)

I would personally use it for at least these:

• Perl script that publishes picture in internet
• One that would mail it to one other website
• One that would make it ready to be attached on new email
• Perhaps one that would open the file in metadata editor

None of those are features that would make sence to include in the program, as they are highly special, and require lots of configuration.