www.lulu.com was founded by one of the co-founders of Red Had Linux, and offers an intriguing self-publishing print-on-demand solution. You can even sell your downloadable books from their site.
I’ve heard of them. There are a number of POD options out there now but some of them seem shady (although it’s possible some writers just don’t do their homework before going that route, get screwed and then complain loudly).
As a satisfied customer allow me to vouch for lulu. Lulu successfully adds value by printing and binding pdf (IIRC) files. Lulu publishes professional looking soft bound books of varying physical dimensions with unique ISBN numbers. You get a book a cut above the typical do-it-yourself publication printed in duplex on a HP laser then velobound.