My library has a banned book clubs for teenagers.

Books don't get banned in my country, but they read and discuss books that are banned in other countries.

Also, you can check out a kill-a-watt to monitor your electricity consumption.

My library has something called discovery kits. They’re large bags with everything you would need to try out a specific activity. There’s all sorts of things, including metal detectors, sewing, astronomy, photography, microscopes, vacuums, anatomy, bike repair, circuits, and so many more. The thing I love about these is that they’re not just a few books about the topic, they really have everything you need. The photography kit has a camera, astronomy has a telescope, sewing has a sewing and embroidery machine, etc.

There’s been a big bump in board games at my library, which I love and I’ve donated to, and one by my sister’s place has a whole tool lending library. Seems super nice for folks that need a power drill once every few years.

Original art (paintings and sculptures) by local artists. They csn be checked out for three months at a time. It's really nice to have some original art in your home even if it it's not by a big name.

Also, I can easily access most of my country's important newspapers' online articles that are normally behind a paywall.

Passes to local museums, gardens, and attractions.

Tools, it’s really handy when I needed a thermal camera for a project and didn’t feel like spending hundreds for a tool that would get used once.

My library has really good access to online catalogs with ebooks, audiobooks, music, and movies. I rarely come across a fiction book I want to read that isn't available, all without even having to go into the physical library.

"Lots of books" may not be the answer you were expecting, but the volume of media they have access to is truly notable compared to any other library system I've ever been a member of.

You don't take it home, but my library has digitizing machines. You can digitize hundreds of old photos in minutes (it pulls them through and scans them like a deck of cards in a shuffling machine, so fast! And it is super sensitive so no/low risk of a photo jamming), and it can scan front and back at once, for those photos granny labeled on the back in her sweet cursive. You can digitize old home movies all the way back to those circular reel movies. All for free, as much as you want. The equipment is thousands of dollars and they just let me walk in and play with it. It's incredible

A robot set for children. The robot is called Dash. It can be programmed with a tablet or laptop using special apps with a neat UI. We had one for two weeks and it was a lot of fun.

Can't take it home, but I'm currently testing out the 3D printers at my local. They also have a 3D scanner.

a metal detector and a bocce ball set

When I was in college, I found a hand-bound report from the Department of the Treasury, written in 1939, about the financial situation in Nanking during the Japanese occupation. I was writing a report about the Rape of Nanking for a history class, and I stumbled upon it while searching the university library.

I was shocked that it wasn't in their archives, and even more shocked that they let me check it out.

Theremin

My local library system has tools, kitchen implements, a recording studio, musical instruments, stem kits for kids, video games, and art.

They need a better inventory system, though, cause all the non-book items are inventoried alongside the books. If you want to rent a shovel, you will see every book with "shovel" in the name before you see any actual shovels.

A soil probe and sample boxes. You use the probe to take what looks like a little core sample and send it off in the box to get a soil analysis from the local university extension (for a nominal fee).

I'm just old enough to clearly remember pre-internet life and library use, so the coolest thing my library has in my opinion is the huge catalogue of books available at my fingertips through their app. No physical item to worry about means no risk of late fees either, it just returns itself if I don't before the rental is up.

There are, like, household tools and stuff available as well as a good catalogue of movies on disc. I avail myself of those now and again, but I constantly have a book or two borrowed. That'll always be my favorite thing my library has.

Car

edit: Electric car from Toyota.

Zoo and museum tickets

Our local library is really cool, it has a recording studio, a makerspace with 3D printers, and a service where you can borrow tools. You can even borrow a radon detector!

Danish libraries provide an online streaming service, where you can watch 2-3 movies a month for free. It's awesome! They even had Everything Everywhere All At Once before any other streaming service here.

If we're talking about the library at the college I go to, besides the wireless hotspots for students that need it, probably all the foreign language DVDs and DVD player (most likely portable)if you don't have one.

Not able to checkout, but my local library has a tiny maker space you can go in and use. It includes some crafting supplies, a sewing machine and a 3D printer. For using the 3D printer they have a stamp card you pay for at the start for hours of printing. It's not expensive, it's there mostly to help pay filament and prevent people from doing super long prints without thinking about it. For checking out they have movie and series DVDs and board games