iPhone: Just before iOS 7 came out, Realmac Software, the developer of popular iOS to-do app Clear, said it would be charging for the newest update to the app. The company has backtracked on that policy a little, and original purchasers of Clear can now upgrade to the new version for free.
Clear's move into iOS 7 was mostly a cosmetic one from an iPhone owner's point of view, but the new app (now called Clear+) is a universal app for both the iPad and the iPhone. If you don't need the iPad app, then the original version of Clear is just fine.
The iOS 7 update integrates the aesthetics of the new operating system design, syncs with Clear+, and has a few minor improvements. If you decided to hold out and not purchase the app again, the old version will continue receiving updates moving forward.
Clear ($0.99) [iTunes App Store]