Specctr | Blueprints for the Web
Instantly annotate and measure your design documents right from Adobe Photoshop, Illustrator and Fireworks. Now available in Creative Cloud.
PNG Express | Automated Design Delivery for Photoshop
… a Photoshop® plug-in that slices and exports your PSD document to individual PNG & JPG assets, and allows you to generate matching design specifications with concise information on dimensions, margins, font features etc.
WireKit
An iPhone App Wireframing Kit — A bunch of Photoshop shape layers to make wireframing your next iPhone app just a little easier.