This page on about.com shows you the different Laboratory Safety Signs and what the pictures on them mean. You can also use them to make signs for yourself and others if you have a lab.
This is a website on all the wonderful things in the world of webcomics.
It includes things on Drawing Writing and even a Podcast. I highly recommend it if you want to learn about webcomics.
The video shows you how to select skin tones in Photoshop CS6 quickly and simply.
It is also vary informative and goes into all the basic things you need to know on the subject.
I highly recommend it.