What's the most important scholarly communication format for your field: books, journals, other?

In sociology the primary publication medium is certainly the scholarly journal article. The most important new research is published in just a few top generalist journals in the field or a handful of well-regarded topical ones, and with a wide and deep array of additional second and third tier journals (both generalist and specialty) almost everything 'publishable' eventually finds a home in such a place. And publishing in top journals is the most important thing one can do in terms of getting academic faculty jobs and getting tenure. Even with deep ethnographic field work that is undeniably intended for a book, a summary or spin-off article will in most cases precede a monograph.

That said, books are a major part of the system as well; especially beyond the highly quantitative sides of the discipline such as demography and statistics (where co-authored articles as well as conference presentations and posters seem more dominant) it is important and prestigious to publish monographs. Really poignant, topical, or widely interesting research may also occasionally turn up in 'popular' publications, including major newspapers or magazines like The Atlantic, though this is not all that common nor all that prestigious or important within the academy.