Half.com is a site owned by eBay where you can sell your crap. The differences are that Half.com's primary emphasis is on media products (books, music, movies), and that unlike eBay's auction system, Half.com lists your items at a fixed price until somebody buys them; there's no bidding.
So anyway, I'm selling my stuff.
When you list an item, you identify it using its UPC code or ISBN number. Great idea. Good system. You wanna buy the movie Dungeons & Dragons? Fine. You're a masochist with bad taste, but fine. You type in "Dungeons & Dragons," and Half.com informs you that 118 copies are in stock, ranging in quality from "brand new" to merely "acceptable." Tying everything together by UPC code is a great idea because once you locate the item you're looking for, all available copies of it are consolidated onto one page. To contrast, eBay's system gives you results like "Dungeons & Dragons: The movie *BRAND NEW*" or "LOTR books like dungeons & dragons!" or "ugly hat good for dungeons & dragons larp," and you have to hunt through a (sometimes very long) list so that you can find and compare different copies of what you're looking for.
The UPC thing is great, but they won't list region-free DVDs and they don't tell you when you're trying to sell one. Instead they give you a nonspecific "this code does not match any item in our database, please check to ensure that you did not mistype it" message. After retyping the code and receiving the same message, I finally notice that I'm trying to sell a region zero DVD. This has happened twice tonight. I have a perfectly good extra copy of Eraserhead, and I can't sell it online. You can't have it, either.
What's worse, though, is that several of my "bargain bin" purchases have the same UPC code. Obviously you don't look at this sort of thing until you're trying to resell it online, but I have eight DVDs (count 'em -- eight!) emblazoned with the code 728665990008. As far as Half.com is concerned, I'm trying to sell several copies of the DVD edition of The Mark of the Hawk featuring Sidney Poitier.
Not one of these movies is The Mark of the Hawk.
I get the feeling that somewhere, somebody with a DVD-R drive and access to a really good copy machine is downloading public domain films from the Internet Archive, cranking out dirt-cheap copies, and selling them to Walgreens at a price just above dirt-cheap.