Picking accessible colours can be challenging, quite often the colours you perceive to be readable don't meet various accessibility criteria (WCAG 1.0, WCAG 2.0). The Colour Contrast Visualiser is designed to help you get the colours you want with a familiar interface. You can find it on the project page.

It's still in beta stage at the moment so there will be a few bugs, and it's not feature complete. I currently find it a useful tool myself, so hopefully you do too.

Any comments and questions can be posted in the comments below.