Tango and I spent an hour meeting some cool kids who are going to read to Tango once a week for the school year. We had a great time - Tango really enjoyed himself, rolling onto his back for belly rubs from all the kids.
We're involved in the R.E.A.D. program -- the kids read one-on-one to Tango. He listens and they improve their skills (he won't laugh if they mispronounce a word, he doesn't snicker if they roll right through punctuation).
If you think you might want to donate some time with your dog to help people, I've got a few websites that might interest you.
First, if you have a puppy, enroll him (or her) NOW in a good puppy class. Make sure the class is taught by a dog-friendly, positive reinforcement trainer, preferably a Certified Pet Dog Trainer. (Check CCPDT or Karen Pryor Academy for a good trainer.)
It's essential to work on good manners sooner rather than later, as jumping dogs aren't welcome in any therapy situations, no matter how friendly they are. Nor are dogs welcome that pull on leash or bark. So it's really much easier if you get your dog started on the right path earlier, rather than later.
The AKC's Canine Good Citizen test is a good barometer of whether your dog is a canine ambassador. It's open to dogs of all heritage -- be they purebred or mixed.
Once you and your dog have mastered the CGC, check out the Delta Society for the next steps.
Once you and your dog become a Delta Pet Partner team, you can begin working to help others! It's well worth the effort you'll put in. Anytime you can spend a little one-on-one time with your dog, it's GOT to be good!