Colorblinding

This is great. It's easy to skip over this and its difficult to accurately foresee (no pun intended) issues for those with colorblindness without a tool like this. This would be a nice addition to @marwannas's Helping Hands collection.

A great eye-opener in terms of accessibility issues for web designers. Some types of color blindness affect approximately 1 in 12 men and 1 in 200 women in the world. There's a nice introduction to the extension over here.

Such a no-brainer. Awesome!