I just sent them five dollars. I wish it was more. I hate being semi poor. (Fixed income) I can always scrape together a few dollars for a worthy charity.
There's something you can do that doesn't involve money (depending on where you are, of course!).
The people who run shelters are amazing folks. But they can't give the time and attention to each resident that they may need.
So - go visit. Sit with the cats or dogs, play with them, talk to them. It makes it easier for them to be homed as they are still socialized. Doesn't do your heart bad either. ^-^
(Disclaimer - three grandkids do this every weekend, come rain or shine. Their idea, too.)