I've been doing a lot of bart/muni travel lately and my Clipper card has been indispensable. Thus, I have some ideas for my first product. I'll be doing research and starting sampling soon...I am super excited about everything coming up. If you have any ideas of how you use your clipper card -- comment below! I want to know what you want and use.
Some awesome things I've found so far (click the images for the link):