Amazon river - books and DVDs
One of the places I've always wanted to visit, but about which I've read little. (See my South America book reviews.)
Wild South America: Andes to Amazon is an excellent nature documentary — and the special feature on river otters is a highlight. Andes to Amazon: A Guide to Wild South America looks like an accompanying book.
For the geology, Devil in the Mountain is about the Andes but touches on the Amazon.