Amazon has launched a Kindle Challenge program for users in the U.S. The invite-only program allows users to engage in Kindle Challenge quests and get $5 in eBook credit. The earned credit will be applied to your next eBook purchase. Amazon has launched a new program for Kindle users, with an aim to encourage reading. The new Kindle Challenge program lets users engage in quests and earn badges for completing them. Users who earn at least four diamond-shaped badges can get $5 in eBook credit, which be automatically applied to their next eBook purchase. Source: GoodEReader Unfortunately, however, the Kindle Challenge program is currently available to users on an invite-only basis. As per the folks at