From Engadget, Apple announced today the ability to purchase at a discounted price the balance of an album from iTunes when customers have purchased individual tracks. Effectively the customers will be getting a $0.99 credit per song purchased previously against the full album cost. This has been a long-standing peeve with the iTunes Store– so this is good news. The downside of it is that you only have 180 days from the single purchase to get the credits.