Fill a backpack full of good things for a homeless person, and then find someone to give it to.
You can purchase cheap second hand backpacks and warm clothing at charity shops, and food and personal hygiene items at discount stores also. For around $20 (depending what country you live in, of course) you can give many comforts to someone who has practically nothing!
Some ideas for the backpack's contents (but by no means are limited to) include:
Personal Grooming:
Fingernail clippers / fingernail files, comb, tooth brush, tooth paste, soap (and soap holding container), toilet paper, deodorant, wipes
Clothing:
Gloves, beanie, warm socks, scarf, rain jacket.
Other:
A blanket, shelter tarp, space blanket, freezer bags / snap lock bags to protect whatever the homeless has left, small umbrella
Nutrition related:
Can opener, plastic spoons, mug, and various food items
Hope:
A book...
