The Rusty Zipper homepage states that they opened in 1995 and were the first vintage clothing store on the net. The selection is pretty big and features pieces from the 1940s to the 1990s, as well as categories like shoes, accessories, vintage ties, and sewing patterns. I'm simultaneously intrigued and horrified by their entire category of Ugly Christmas Sweaters.
The prices can be kind of on the high side, but things are returnable (within 15 days) usually one-of-a-kind, and they are very clear about any damage the item has sustained prior to purchase. If clothing isn't your thing, but you're still looking for something retro it may be worth your time to check out their other odds and ends. I'm sure that someone has a need for ceramic ashtrays in any color and shape, an aluminium Christmas tree, or 1970s sitcom posters.