The library can greatly increase the power of your dawah efforts by providing a repository of useful materials and other resources that new muslims or persons interested in Islam could browse, view and listen.
Free islamic literature is available from some organisations and groups and may form the basis for the start of an islamic library collection. At present I have found Islamic Dawah Central International to offer some materials without any cost (except maybe shipping and handling fees). The Discover Islam Center gives you access read copies of books online and has books available for free. For brochures and pamphlets about Islam place your order at Why Islam?