Anime News Network
Anime news plus a database of about every anime and manga title. So helpful in researching anime and manga.
My first choice store for my anime DVDs and manga. Good store, they have a lot of sales too.
A DVD rental website made especially for anime.
An awesome website full of scanlations of manga.
Yeah, everybody knows about e-bay, but you can find tons of anime and manga stuff there!
The Otaku Fridge
A great fansite with tons of anime reviews and a few for manga.