Donate your time
If money is tight for you but you still want to help out your favorite non-profit groups, why not donate your time? I can guarantee you that way more people donate money than time, and that all of those non-profit groups desperately need people to help pick up trash, serve meals, and build trails. Volunteering is a great way to teach kids about giving back as well. If you're looking for a way to donate some time to a group in your community consider one of the following:
Help build or maintain bike trails with COPMOBA.
Volunteer with Catholic Outreach for everything from story readers to dishwashers.
Roice Hurst Humane Society currently needs dog walkers and other volunteers.
Here's a photo from last year when I volunteered with COPMOBA to work on the Three Sisters trails. Everytime I ride this trail I feel a sense of pride knowing I helped. And hey, sometimes they even give you beer after you volunteer!