LightZone, once discontinued, has been restored to life as an Open-Source project. It is still being developed and improved, but downloading the application requires creation of an account and logging-in to access the download.
You can read the project's rationale behind the download requirements, and can create an account--or log-in to your account--from the right side of the project's home page. When first creating an account, you'll have to open the e-mail sent from the project and click on the link to confirm your request. Once you're logged-in, you'll find the download link on the left side of the page: "Click Here for Links for Downloading and Updating (Wintel, Mac)".