Index Cards Come In How Many Colors?

I'm going shopping for index cards later this week. I read Pick A Card, Any Card at R.L. LaFevers' blog (referred there by Becky Levine), and now I'm thinking that colored index cards could help with the story arcs (which are like mini-plots) in the 365 Story Project. They could certainly help keep track of characters meandering through the year of stories.

I'll let you know how that goes.