A program which automatically shuts down your web site at different times for different people, based on the location of the person visiting the site.
As the site says, "When a visitor comes from a place that's already Shabbat - your web site will be closed for him, while for one that arrives from a place that it is not yet Shabbat - your web site will be opened."
The obvious question is: The only people likely to buy this are Orthodox Jews, and how can they be sure that it works? Wherever they go to test it, if they themselves aren't breaking Shabbat, there will be no indication that the software is running! (The obvious answer: learn to use SSH.)
Sometimes, Google ads are interesting enough to click on even when you know you won't buy anything. I clicked this time, and this is what I found.