Another feature I'd like to see in IzPack is being able to use variables for adding files.

Example use case:

My project ships in multiple flavors, they all have a very similar design but each flavor need to include a, say, different database dump. Now I would not like to maintain multiple configuration files, but rather have a install-base.xml containing basicly everything (and a <singlefile src="${FLAVOR}.dump" ...>) and a install.xml which looks something like this:

<?xml version="1.0" encoding="utf-8" standalone="yes" ?>
<installation version="1.0" xmlns:xi="http://www.w3.org/2001/XInclude">
	<xi:include href="install-base.xml" />

	<variables>
		<variable name="FLAVOR" value="foo" />
	</variables>
</installation>

Now I could create one of these small files for each flavor and adjust the variable, and every flavor would use the same configuration, but a different dump file.