When building products (digital ones but this could also apply to other products), color choice is important. The color can convey your brand identity, help users understand information, etc.
Designer and illustrator Geri Coady authored an interesting piece about designing for people who are colorblind on the web design blog 24 Ways to Impress Your Friends. Coady provides background about colorblindness and explains how it can affect the usability of various visual media such as websites, graphs, maps, and even video games. Coady also explores design solutions that can provide color accessibility.