The generatedata.com public site has been around since 2005 to provide an online version of the open source script. To cover hosting costs, we added an option for people to donate/register for a user account on the site. This lets them save their data sets.
The same functionality has always been available on the open source version - you just need to download and install the script yourself.
Over time we plan to continue expanding the website's functionality beyond the open source version, namely to target it more towards businesses and offer different ways to group and share data sets.