For self-publishers, choosing between Amazon's Createspace print on demand service, and Ingram's Ingram Spark/Lightning Source service can be difficult. Both services have their pluses and drawbacks. For fence-sitters, here's an article that argues uploading to both services is a good idea. An author client recently indicated this approach was working well for him, and we'd be happy to hear opinions either was other print on demand using authors.
One of the benefits of digital printing combined with online bookselling is the capacity of printing books as they are ordered, rather than pre-printing and warehousing. This massively reduces costs for small presses and self-publishers. Two major players dominate this field — Createspace, owned by Amazon, and Ingrams Spark (Lightning Source in Australia). The two services offer a very similar level of functionality, but there are differences in pricing, approach, assistance and sales channel availability. Check out these interesting articles discussing the relative merits of each service, and identify which one better fits your particular use-case.