another thumbs up for amibay!
Their rules may seem unusual at first, but I find they are very well thought of, making it a great place to trade, very civilized.
Also I find that amibay is full of other interesting content whose quality is hard to match nowadays in other amiga sites - Their Amioracle section is full of eager, knowledgeable people and I've learnt a lot just browsing it. Their Photos section is also very keenly updated (unlike unfortunately a.org's) - I've been meaning to contribute to but never get the time!
