I've got some stuff that I've been meaning to sell, but I've been procrastinating because I don't want to have to deal with shipping it. Your idea made me think that I could just sell the items using Craig's List or the local classifieds. I'll just include that I only accept bitcoins. Of course the payment is non-reversible, so I'll probably let them bring their laptop to my house and use my wireless connection to pay me.
If you make a classifieds site, you should act as arbiter. The buyer sends you the bitcoins and when either the seller can prove that he sent the item or when the buyer confirms that he got the item, then you pass the bitcoins along to the seller. Of course if you don't want to act as arbiter, then you should set your site up for local transactions, like Craig's List.
Is that how escrow works on ebay?
My site is just a go between.People post an ad and buyers contact them.They can be located anywhere it is not preset to a particular location.