There's a collectors website over in Europe called Colnect (for Collect = Connect) that lists all sorts of collectibles where you can trade and talk with other collectors, etc. and it's totally free although they do offer a premium membership with no advertisements. There are 16 major categories, including a HOTEL ROOM KEY section with over 75,000 cards listed plus they have a smaller CASINO CARDS section but that only lists a little over 1,500 cards currently so not very useful yet. Other categories include Phonecards, sports cards, postcards, tokens, gift cards and a LOT MORE.

Here's a link to their Hotel Keycard Page.... you can change categories and roam around from there with the Categories button on the upper left

http://colnect.com/en/hotel_key_cards