GOG.com has worked up another interesting sale scheme you might want to take a look at. The "DRM-Free Time Machine Sale" started this morning and will be offering deep discounts on games from GOG.com's collection of classic computer titles, one at a time, for a limited time. How limited that time is depends on you, as purchase of the current title extends the time it's available at that price for an additional three seconds. Even if you don't choose to buy, you can have an impact with up-and-down voting which adds or subtracts a second. When time expires on a deal, it is then replaced with a new offer.
This is a much better idea than their prior, "limited number of copies" promotion, which went great until a game came along which nobody wanted and stalled out the progress of the sale for hours. Allowing shoppers to downvote to get the next deal a little faster ought to compel a little participation.