PSDTUTS is a site with lots of Photoshop tutorials. Ian Yates has produced a comprehensive tutorial on the Photoshop Pen tool. Mastering it will improve your ability to make selections and knockouts.
Variations on the Pen tool are used in many Adobe products, including Illustrator, Fireworks, Premier, and After Effects. So getting a firm grip on the Pen tool is a good skill to have.
This is part one of a two-part series where Michael Gray helps readers better understand color management. Many of the tutorals on the Web that cover color management for photographers, look at it from the perspective of Photoshop. Tis tutorial instead focuses on Lightroom and Melissa RGB. What's Melissa RGB? Click the hyperlink and read Michael's tutorial to find out.