I would like to second Steve Gubkin's point. While it is not as good for your paper count, publishing things together as a single item is not only kind to the reader, it also places your work where it is more likely to be read, or at least cited. I remember a conversation long ago with John Ewing, then Executive Director of the AMS. He told me of everyone's surprise, after the introduction of the Citations addition to Math Reviews, that books were (and I'm sure still are) cited far more often than articles, way more than one would guess by perceived quality. Books include things like Memoirs of the AMS and Asterisque volumes, for example.