Here at the library we use a variety of open-source software to serve our community.  Software used includes:

Koha Integrated Library System
“Koha is a full-featured open-source ILS. Developed initially in New Zealand by Katipo Communications Ltd and first deployed in January of 2000 for Horowhenua Library Trust, it is currently maintained by a team of software providers and library technology staff from around the globe.” — Koha.org
This is free software that we have hosted, and administered for us by LibLime. This software will save us thousands of dollars over our previous ILS, which was a proprietary system. Download Koha for free, here.

Ubuntu
“Ubuntu is a community developed, Linux-based operating system that is perfect for laptops, desktops and servers. It contains all the applications you need – a web browser, presentation, document and spreadsheet software, instant messaging and much more.” — Ubuntu.com
We use this, free, linux operating system on several of our machines. It has helped us speed up the process of checking in & out books at the circulation desk. It has also enabled us to re-use older machines that we would otherwise be unable to be put to any good use. Interested in implementing Ubuntu in your public library? Our technology blog has information you may find useful.

Firefox web browser
“The Mozilla project is a global community of people who believe that openness, innovation, and opportunity are key to the continued health of the Internet. Since 1998, we’ve worked to ensure that the Internet is developed in a way that benefits everyone.” –Mozilla.com

WordPress blogging software
“WordPress is a state-of-the-art publishing platform with a focus on aesthetics, web standards, and usability. WordPress is both free and priceless at the same time. More simply, WordPress is what you use when you want to work with your blogging software, not fight it.” — WordPress.org
We use wordpress for our library technology blog, and for this website.