The Wishlist section would have two tabs: "Public Wishlist" (the current one) and "Private Wishlist" (the new one). When adding a game to your wishlist, you could choose which list to put it in (for example, via a dropdown menu). There should also be an easy way to move games between the lists. The Private Wishlist would not be shown on your user profile, would not be visible to friends, and would not affect the "Friends Wishlist" Steam recommendations. Only the account owner has access to it. To keep the system useful for developers, games in the private wishlist could still be factored into personalized discount algorithms and recommendations from Steam (so developers can see overall demand, but not specific accounts).