Helping animals is very rewarding.
ToBeMe: You're right, unles you volunteer/work in a no-kill shelter, a lot of animals will be put down. I wouldn't be able to handle it. I'm the person who saw the neighbor's cat limp onto my front porch badly wounded and burst into tears (I took him inside and cared for him until he was healed). I just couldn't put an animal down, especially a healthy one that is just being put down because of shelter overcrowding.
Zoltar: Go for it! Cleaning cages is not fun, but a clean cage means a happy animal. I've seen pet stores where all the animal has is a food/water dish and a litterpan, no toy, blanket, anything. If you can't volunteer, then you could certainly donate toys, blankets, etc to make their lives more comfortable.