NMAI has begun putting images of its entire collection online. Their press release says they have more than 800,000 items so the entire project may take some time :-) There's a nice Washington Post article about the project. There is a search page for what is already online at http://www.americanindian.si.edu/searchcollections/home.aspx
Some of the objects are really beautiful. I was going to include one of them here, a Quileute adze with bird effigy handle. But it turns out you have to pay the Museum for permission to reproduce their images on a website. (Free for one-time use in a school project. Go for it!) So just click here to look at it.