Some time ago, I found a great white paper on creating white papers, written by Michael Stelzner. Often in working with sales teams, we talk about positioning yourself as a consultant and even as an expert (if you have earned the right) - which you can do by writing a white paper.
I've found that many people don't know how to write one, so try these tips - and link to the shortened version of the article to get even more info.
One of Michael's tips:
Decide On An Approach
-- There are really only two ways to write white papers: (1) by focusing on your self-interests or (2) by concentrating on the interests of your readers. The self-interest or "chest-beating" approach focuses exclusively on a product, service or solution by expounding on its benefits, features and implications. While effective in some circumstances, this approach is best left for something other than a white paper, such as a data sheet or product brief.
I use two whitepapers and am working on a third. Many clients find the value in them if they are prepared right. They take time to develop, as well - so be sure and factor in that development time.
Final point: consider using clients and prospective clients or industry experts as a part of your "R&D" team - and poll them on topics which you can then write an objective white paper on.