(b) With (a) in mind, there really needs to be a way to plot to/from somewhere other than (what the iPhone thinks is) your current location.
(c) It would be great to be able to see bike lanes, but I understand how much extra effort that would require; so don't sweat it, but if this does rise to the level of a business...
(d) Get rid of the icon-sheen in the App store. It's not enabled on the actual phone icon, and it looks so much better that way. It looks cheap with the sheen in the App-store: http://stackoverflow.com/questions/4087500/does-itunes-store...