If you're just lending books out of your library, then a number of the solutions mentioned above may work well. If you're also (thinking about) lending tools or other goods from your lending library, then you might want to check out Local Tools. It's a web-based lending library management system.

According to the features page, it will calculate due dates, late fees, send out email reminders, track donations, and more.

So far all the exhibits are produced by and funded by pesonal donations (the main one from Dr. Daniel Koshland). Hopefully the endowment will continue and donations will keep furture exhibits corporate sponsorship free.