Here's a website
that has an index of many many charities, organized by state, so you can find one near you.
I started making charity items, but never sent them in.
I wanted to make more before sending them in, but have been so busy with other projects.
I really like the idea of knitting chemo caps for cancer patients who've lost their hair. Headhuggers has great patterns for this purpose (I've got lots of her patterns in the hats section of free patterns).