If you've designed a cross-platform application then you want a cross-platform way of allowing people to install it.
For all it's faults, Java is probably still one of the most sure-fire ways to ensure that your installer works whether the user is installing it on Windows, Mac or Linux. GlassWorks allows you to do so via a fairly easy to use interface that enables you to provide installers via web links or self contained packages.
You can make your application associate to certain files or extension types and ensure that it only installs to predefined locations on a users PC or Mac. In addition, you can ensure that your installers display certain messages and logs while installing so it's suitable for ad supported downloads or installs.
Even those with little development experience should be able to find their way around Glassworks. The application is well organized with different tabs relating to different aspects of putting the installer together.
Probably the main drawback is that overall, zip packages are generally quicker than Java installers but this application allows you a high degree of customization that is perhaps not possible with the former.