Rightstuf is the main place I get my anime, though I've been known to pick it up via Amazon, Wal-Mart, Best Buy, Deep Discount, etc. It's been awhile since I've bought manga, but I usually pick that up at a local bookstore like Barnes and Noble, Borders, or Books-A-Million.
Also, thanks for the link to that extension, Mynd. That's very cool; I'm gonna try it out.