Autumn leaves is a great bookstore and fits in perfectly in a liberal, hippie-ish town like Ithaca. It is located down in the Ithaca Commons and is a great place if you are looking to avoid the massive chain stores that have cropped up in the area downtown and by Pyramid Mall.
They sell new and used books. I have been in there several times, once to buy and other times just to peruse. I like their selection and the ambience of the store.
The clerks are always extremely friendly and willing to help out and I have never had a problem with any book that I bought there.
I would recommend this place as a nice alternative to the bigger stores, especially if you are looking for a hard to find book or older, collectible editions. Also, stop by even if you aren't looking to necessarily buy a book, just to browse.