TL;DR
Before you buy something, see if you can borrow it from the library
Reserve free tickets to local museums and attractions
Print out your documents at a discount
Get free help with homework and standardized tests
Take free fitness, hobby and language classes
Attend free concerts and performances
Access free social services
Also rent DVD and Blu ray discs for free
Or access to free streaming of movies
And video games, including new titles, if you don't mind potentially waiting just a little.
As someone who spends a lot of time in coffee shops (working, reading studying), the library is a nice change of scenery and you don't have to buy anything to justify taking up space. A lot of libraries are stunning too.
Also they get you access to audiobooks which are a great alternative to paid subscriptions. I do have a libro.fm account though to support my local indie bookstore.
This is great! Many things I didn't think of...
My mind was blown when I realized my library gives you $3/day of free printing (@10c/page). I will never pay to print anything again, since I mostly have random 1 off things to print every once in a while.
A library where I used to live in PA kept small household tools and appliances for checkout. Great for when you need a Kitchenaid mixer three times a year.
Discuss how to save money.