https://squareup.com/ might be an option for accepting credit card payments.... the logistics of actually doing it are a little beyond what my brain is willing to handle at the moment but it presents a path that may be walkable.
Squareup looks like it might be pretty awesome, just in general. At first glance at least.
Wrt Bitcoin, it could be excellent for face-to-face transactions. Swipe the card, wait for the money to clear, use your phone to send the bitcoins. Though, I can't imagine how there would be a significant amount of business for someone selling bitcoin in the streets like that.