Both are great organizations, but I found you need to be a bit patient for them to follow up on the contact info you leave behind. Through volunteer match, I had volunteered for SCORE (a service corps of retired executives who counsel small business owners) and did some pro bono PR/communications and newsletter work and am currently involved with a local non-prof adult ed effort through a church for United Way (tech ed). I'll vouch for volunteer match!! SCORE and the adult ed group are great organizations.

There are so many more orgs that need help than those with children and animals. You'll be amazed at what you can find.