Tips for starting a company book club

We are looking to grow the developers at our small application development shop. We want to get them interested in new technologies, concepts, patterns, really anything that could expand the type of clients we can service, as well as increase the skill level of all of our coders. As well, we want to grow the camaraderie of the department, most everyone is silo'd away on individual projects and we want to get us all working together more often. One of our ideas for this is a book club, so I'm looking for any suggestions. We're primarily Ruby/Rails and iPhone, and while I'm open to books about that, we really want to be more generic or hone in on technologies we haven't used yet. If your company has done a book club and you have any tips or tricks for it, or have a suggestion for a good book, I'm all ears.