We use Wise which uses a scripting technology. Our build process (using Visual build Professional - highly recommended BTW) edits the script to suit changes in the stuff being packaged like version numbers etc.

We are using a fairly old (8.1) version of Wise InstallMaster, but the system works pretty well for us. We generate a lot of similar installers for different modules and it's pretty much just a case of copying a build folder and renaming it to get the build set up for a new module. (There's a bit of magic at various levels going on fo that to happen :) )