PSAlertView & PSActionSheet
Update: Look into the more modern PSTAlertController instead.
Block-based subclasses for UIActionSheet and UIAlertView, extracted from the commercial PSPDFKit PDF framework, because I love open source.
PSAlertView uses ARC and is tested with Xcode 5.1.1 (iOS 6.0+)
I'd love a thank you tweet if you find this useful.
PSAlertView is available under the MIT license. See the LICENSE file for more info.