Page Layers is a nifty little app that converts webpages into layered Photoshop files. You can open and edit entire webpages as PSDs, perfect for late stage editing.
The 960 grid is a simple but effective grid system that comes with PSD and CSS templates to translate your perfectly proportioned site to the web with ease.
Web Font plug-in
Web Font Plug-in is a handy tool that lets you use Google Fonts in Photoshop, meaning you won’t have any nasty surprises when you move from PSD to CSS.
Pixel Dropr lets you create libraries of UI elements and images and instantly drop them into Photoshop as you’re working. Great for prototyping.
Cut&Slice allows you to export assets for different devices quickly and efficiently. If you do have to slice up a PSD, use this tool to improve your workflow.