Igor in character selection, pressing ESC/view - Player/Lobby Info will show the the team you're playing on and you can see messages from people, who are off the screen
This one's really useful, @Igor. I had no idea you could do that from the character selection screen. I've always struggled massively when it comes to knowing who my teammate is. I don't like starting the first round just hitting everyone, so usually spend the first 10 seconds avoiding all of the players, just trying to figure out who I'm with. The number of times I've died while trying to find my teammate is the stuff of legend, so this one's going to make a big difference. (Okay, I'll still be pants, but at least I'll know who's on my side.)