Holding an arts bazaar in your library space, partner with community artists, and get lots of people to come in and see what your library does, and ask them to make a contribution. Allow them to come and talk about what the library means to them, and how the community can continue to support the library.
Partner with a local technical non-profit organization to allow them to hold computer classes in your library, particularly classes on information and digital skills literacy for example digital assets estate planning and on-going digital rights; even doing some joint spring fundraising together to acknowledge the new role of libraries in enabling low income people to use technology.
Lease space in the library to other small businesses.
Selling T-shirts, bags, pens and key-rings.
Ask college/university student union club/societies to organize social gatherings for your library.
Get a group of cyclists to do a long ride for your library, and get people to sponsor them.
Hold a festival around your library cause and ask people to make a contribution.
Art show and sale auction.
Fashion show and auction off fashion clothes.
Author luncheon, author reading and author signing.
Craft show and sale.
Other fundraising activities to consider: jumble sales, read a thing, interest groups conferencing etc.
Charge groups for meeting rooms.
Financial literacy classes/sessions from understanding your tax to budgeting your shopping bill.
Pro-bono law students taking on cases to offer as legal drop-in services.
Career information drop-in advice service.
Knowledge Cafes for specific user groups underrepresented.
Living library or Human library
Business start-ups sessions and advice