We already mentioned this one in a previous post back when it was still in Alpha, but now it is in Beta and available on the Asset Store officially. I can't say enough good things about Shader Forge. The developer is extremely active in improving this visual shader editor and we use it for all the shaders in all of our projects now. This isn't just a tool, it's an investment in the quality of your game's art. If you come up with an awesome shader you could even put it up on the Asset Store yourself!

VPaint: Advanced Vertex Painting - by Valkyrie Entertainment