Joel Greenwich has an impressive single-card color change available over at ArtofMagic that comes with a little something extra: good karma. Proceeds from the sale of Catalyst will benefit the M. K. Ghandi Institute for Nonviolence. Learn a slick trick with several variations, do your bit for world peace. Not bad for seven bucks. 

Buy Catalyst from Art of Magic

• Category: Sleight of hand 
• Price: $7
• Format: Download