I take it that you are talking about books here, rather than journals. With journals, a way has been worked out, using the publisher's permission to post the final draft that is accepted for publication after peer review. The majority of journal publishers now accept this. Here's a look-up service to check publishers' policies http://www.sherpa.ac.uk/romeo/
With books, while such policies have not yet been worked out, authors could try the same route, as often the same publishers are involved. Or you could approach an open access publisher such as Athabasca University Press or Open Humanities Press, with print-on-demand copies available from both for Tenure and Promotion Copies, or for libraries to purchase. AUP also sells e-book editions which do well, despite the free PDF they also offer.
Hope that helps, as your support for open access is appreciated.
John Willinsky, PKP