Using GCD and blocks to make working with Core Data stuff in the background more sane.

JMWhenTapped is a simple little syntactical-sugar addition to all UIView objects, as well as any class that inherits from UIView. It allows you to assign touch-up, touch-down, and tapped (touched down then up) actions to a UIView object using a convenient blocks-style syntax.

KVOBlockNotificationCenter is a set of source code for using blocks with Cocoa's Key Value Observing (KVO).

The iPhone needs a better way to make HTTP requests, specifically calls to REST web services. Seriously mixes Blocks with NSURLConnection & NSOperationQueue to do just that. It also will automatically parse the JSON response into a dictionary if the response headers are set correctly.

More examples of working with blocks in Objective-C.

Best tutorial on the basics of blocks I've found. Of course, I'll never actually remember the syntax.

More examples of using blocks to improve transactional code such as NSGraphicsContext, CATransaction and more.

addObserverForKeyPath, powered by blocks.