Though the iPhone's virtual keyboard has been named one of the best in the business, it still lacks a fairly major feature: haptic feedback. The little vibration that lets you know a key has been pressed is on nearly every other touchscreen smartphone on the market, but not the iPhone.
Luckily we have the jailbreak community to produce apps and tweaks that makeup for iOS shortcomings. Though there have been haptic feedback utilities in Cydia for quite some time now, they've never really impressed me. They always seemed to make iOS slower and less reliable, until now...