I certainly do admire many of his books. Ringworld and Footfall are two of my favourites and could be used as supplements to high school or first year university physics classes.
In Footfall, a novel about the invasion of Earth by elephantoid (not exactly elephantine - not giant, but elephant shaped) aliens, the US government gathers a group of Science fiction writers to provide outside-the-box ideas and suggestions on how to fight the aliens.
Such a group -the sci-fi writers, not the aliens - does exist. Their acronym is SIGMA and it means something important, I'm sure. At a recent Sigma meeting (the link took me to the article i wanted, a quarter of the way down the page), Niven told Homeland Security that to keep hospitals financially viable, they should create rumours in Spanish that the hospitals are killing patients and harvesting organs. That would drive away illegal aliens (of the human sort) who typically don't pay for medical services and keep the hospitals available for legal citizens.
I learned of this from Boing Boing -do I need to hat-tip a blog that in one day will have more visitors than I ever will?
Kevin has been ahead of the curve in questioning Niven's current relevance.
The Baen free library has a recent book by Niven, Fallen Angels. The book is passable but the library is great. It offers the first or first few books in various Science Fiction or Fantasy series' for free. There are also a few freestanding books by prolific authors to get you interested in their work.