Umbrella organization that gathers together a nationwide network of independent US booksellers. Buying local ensures that almost half the money will stay in the community, and indie bookstores are the last bastion of literary community events, knowledgability, and customer service.
National Book Critics Circle
PEN American Center
Speculative Literature Foundation
BetterWorld Books
A socially-active online bookstore selling new and used books at competitive prices (with free shipping within the US, and only $2.97 to anywhere else in the world), with proceeds going toward worldwide literacy and education programs. Books donated and sold through the site avoid piling up in landfills, and shipping is offset by purchasing carbon credits to decrease their ecological footprint. Inexpensive books sold with an environmental and social conscience; what more could you want?
LibraryThing
For those of us who feel compulsively urged to catalogue all our books. There's also a great social aspect as well, since people can comment on each other's libraries, and get recommendations on similar books. Books + geekery = LibraryThing.
Moleskine Asia
The Asian site for Moleskine, maker of my absolute favorite notebooks in the world. I've been using them for years, gathering them up and hoarding them before their popularity recently surged; they are portable and fit perfectly in your pocket, their hard (but not too hard) covers give enough support to write anywhere, the sewn-in ribbon allows you to easily find your place, the memo pocket in the back holds odds and ends, and the elastic band binds everything nice and shut for traveling. I use them to jot down story notes, write first drafts, and make hasty sketches; it's perfect for the Vagabonder on the move.