Help new parents have access to the resources they need to be successful
Sometimes, abusive situations arise when an inexperienced parent is frustrated or loses patience. A new parent is less likely to have such feelings if they're prepared and ready to have a child. Make sure your public library has resources for expecting or new parents.
Go to the library and see if you can find parenting books yourself. If you can't, ask a librarian where they are. If the books are there, they don't do much good unless they're easy to find.
Ask parents you know for recommendations for parenting books. Talk to local pediatricians, day care employees, and teachers as well. Pass on the recommendations to the library.
If you feel the library's materials are too few, there are plenty of ways to get the books that you need. Try running calling publishers or bookstores and asking for donations. Have a book drive for used books in good condition. Run a babysitting workshop for $5 and use the money you make to buy books for the library. The more people you can get involved in these projects, the more successful you'll be!
Obviously books belong in a library, but local libraries often serve as sort of community centers. See what other services and resources your library might be willing to provide. Maybe they'd be able to host parenting classes. They might also want to expand their parenting section with media besides books. Look into magazines and DVDs.
Make it accessible
See if you can establish a whole, easily located parenting section. Maybe put it near the kids section or a playroom, if your library has one. Make sure you advertise the new and improved parenting section of the library! People have to know where to find the resources they need.