I wrote an iPhone app for rare book collectors called Titlz. http://davidlains.com/titlz http://davidlains.com/titlz The market for this kind of app is tiny but

I wrote an iPhone app for rare book collectors called Titlz. http://davidlains.com/titlz http://davidlains.com/titlz The market for this kind of app is tiny but I still had fun building it and learned a lot. It has made about $20 in two months.