I joined the Friends of the Morse Institute Library. I read a ton of books thanks to the library and really love how their Friends group has made commitments to the library, so it was a no-brainer for me to join.
If you can do so, you might consider joining your local friends of the library, or friends of the museum, or friends of whatever-civic-organization it might be. I know when I worked at my former place of work, the Friends were very generous and allowed us to purchase a lot of bigger-ticket items we couldn’t normally fit into our regular operating budget, as well as sponsoring programming for students. That’s a kind of philanthropy I can get behind. (There are other kinds I can get behind too, but I’m not talking about those right now.)