GM's can now put players on the 'Trade Block'. This is a space where players can be advertised as trade bait to let the rest of the league know you're looking to make a move. You can add players to your Trade Block and view who's on the block around the league on the Contracts page, and there's a summary in the Tools Tab if you're using a Standard team or a Membership.
Add players to the Trade Block
Check out who's on the Block