Publications are not the magazine or newspaper of yesterday, they can still be that but they are now much slicker and usually electronics. From slide show presentations turned in eBooks or White Papers to publications started as an ezine (or electronic magazine), an eBook itself, or a white paper; the possibilites are many. Of course with the advent of self-publishing and books on demand producing a traditional print book is also quite easy and affordable. Anyone can start a publication with very little money or effort nowadays. Publications on the internet are particularly important because they can establish a level of competency and authority on a subject matter for the author. More importantly, they can be used as giveaways to obtain a good targeted mailing list as well as viral marketing for the author or the company.
eBooks are particularly great to use in viral marketing as a good eBook is passed around from person to person and creates buzz. eZines are also becoming quite popular and they also provide SEO opportunities when also published online. In a way a blog is a publication as well as it is like a
magazine with many articles!