Best for: Research in the days leading up to Black Friday weekend
The BFAds.net website posts and catalogs Black Friday ads from just about every store you can think of, usually before they hit newspapers. Their app has the same access, allowing you to browse the Black Friday deals of every store ahead of time. You can also narrow your search to specific items, and compare prices between stores. The app will send push notifications when new Black Friday ads are released, and when online sales on Amazon and other vendors go live.
Cool feature: The "hot deals" tab in the News feed, which lists real-time bargain releases on a wide range of products (and not just for Black Friday). At the time of this writing, deals included a Blu-Ray box set of all eight Harry Potter films for $43.50 from Amazon UK and a free game download from XBox Live Marketplace. The deals are updated year-round. Click here to get the apps.