I have had a play around with Amazon CreateSpace self-publishing platform, using my MSc dissertation as a manuscript, and am now the proud author of a self-published book. It is available on Kindle and in hard copy in a few days. The process was pretty straight forward, so I am definitely keeping this in mind for future projects. I am not sure how much value it carries towards my academic career, but I feel self-publishing is a way of sharing information which would otherwise just gather dust.
A good post on the topic of academic self-publishing can be found here. It is worth a read, whether you agree with the concept or not. I kind of enjoyed the process of creating something new, and am happy my early research is now available to the whole world, rather than just the student who happens to come across it in the Writtle University College library.