Here are some awesome Adobe Illustrator and Photoshop tutorials that we recently shared via twitter@99designs.
Illustrator
Create Courage, the cowardly dog in Illustrator

A complete guide to drawing evil vector skulls in Illustrator

How to create a grainy abstract lines poster design

Create plants vs. zombie type in Illustrator

How to create a vector sponge art effect in Illustrator

Create a simple compass icon

Video tutorial: get the most out of Illustrator’s Blend tool

25 Tutorials for learning character design

Photoshop
Create an A3 electro event poster

25 helpful tutorials for lighting effects in Photoshop

Give your Photoshop illustrations a retro look and feel

The best new features of Adobe Photoshop CS6

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