Valve have now implemented a new "Trading" section on every Steam Hub which you can post in and people can send you trade offers. Please post anything related to trading in that forum.
Link to whoever reads the topic http://steamcommunity.com/app/225140/tradingforum/
Original Post prior to 3/08/2013:
All in the title really.
I've had to delete too many threads recently with people wanting to trade their coupon for cards or other stuff. Trading in not allowed in this forum (and a lot of others) as it says here https://support.steampowered.com/kb_article.php?ref=4045-USHJ-3810 in the Discussions Rules and Guidelines.
However, you may initiate a trade if you plan on giving it away for nothing in return.
If you fail to meet this rule then your topic will be deleted. Continued topics will end in a ban from this forum.