Our shul library has been neglected for many, many years, and b'h' we are finally cleaning and organizing it. We have some great books, but I'd like to know of some resources identifying important books that we should make sure we have in our library.
Libraries vary significantly from shul to shul based on the congregation but there are some standards that are common across the board and which would be missed if anyone tried to use the shul library for studying.
Most shul libraries will have many more books than this, depending on the interests of the members but these are the basics. All of them are available in English and some in other languages as well. Which ones you get, and which editions obviously depends on the needs of your community.
The Lubavitcher Rebbe emphasized having at least the following Seforim in order to fulfill his directive, known as "Mivtza Bayis Molei Seforim", of filling up Jewish houses with Seforim (list in no particular order):
Chumash, Tehillim, Siddur, Tanach, Kitzur Shulchan Aruch, Tanya, Talmud. (See here)
A Tzivos Hashem Children's handbook (not available online) also lists a Haggada.
Of course this is only a small list, and should be expanded upon according to the means and needs of the specific shul.