For general feedback about the game.Steam Support
Visit the support site for any issues you may be having with the game or Steam.
Yogscast just opened their yearly charity fundraiser: the Jingle Jam 2015! Donate at least $5 to receive two unique, custom-made TF2 items. If you're feeling particularly greedy, you can donate $25 to receive a host of awesome games, like Chivalry: Medieval Warfare, Medieval 2: Total War, Torchlight 2, and many others.
And remember, 100% of the proceeds go to amazing charities like Oxfam, Doctors Without Borders and Mental Health Foundation. So head on over and join the festivities!