Anybody know any good online used book stores? I’m looking for sources in addition to the obvious Amazon and B&N Online. If possible, sources that you have had a positive experience with.
Any and all suggestions will be appreciated. 
I’ve used www.abebooks.com over the last year to buy four books, all from different bookstores. Haven’t had a problem with it.
http:/www.bibliofind.com was the best, though it’s not a part of Amazon.com. Still, it polls used bookstores and you’ll get the most hits.
If you’re desperate, use http://www.alibris.com, but be prepared to pay twice what you’d pay a bibliofind.
YMMV, but I’ve had good luck on www.bookemporium.com for finding both new and used trade books and textbooks.
Well, Powell’s ain’t bad.
I like half.com, too.
Thanks to all for the sites. Now to get started with the shopping…
Best one I have ever used is bookfinder.com. Best selection, best comparison-shopping; I’ve found books I hadn’t even known existed, doing word- or author-searches.
Second that on bookfinder.com. It’s a meta-search site that searches about 20 online databases, including abebooks and alibrus, although not half.com.
Alibrus used to be far more expensive for the identical book. You could tell they were identical because a bookfinder search would pull up the exact same wording on a listing from alibrus and from another site. Alibrus prices were always much higher.
This no longer appears to be true. I recently did a huge amount of seaching on about 50 books on bookfinder. The Alibrus price was almost always five cents less than the other listing’s price. Its shipping fees are fixed and were often lower, especially lower than priority mail. Shipments were just as prompt from the Alibrus dealers.
The advantage of Alibrus for me is that you can use a credit card with them even for bookstores that don’t accept credit cards on their own sites. This made it much more convenient for me.
Here’s a third on the bookfinder.com . Also, check out www.half.com , which is a division of Ebay (set prices instead of bidding, though.).
And a fourth for Bookfinder.com…but sometimes, when the sites it checks are busy, it will skip them, so you only get a partial search. If that happens, I will also check addall.com - it is basically the same as bookfinder, but sometimes, addall has listings that bookfinder doesn’t (and vice versa)
Best of luck.
I love Hamilton Books, not used but overstocks, etc. I have had great experience with them. I have even found a textbook or two that I needed for class.
Sorry, that should be www.hamiltonbook.com 