So how can we file a complaint? What action must we take?
Well, writing everyone is a good start. Letting Steam know you are doing so under duress and have it document isn't a bad idea. If someone starts a lawsuit I'd help organize a blog, wiki for the cause.
Local Attorney General is probably the best bet. If enough people write them, things happen. There are some states where certain terms don't work. If enough areas don't agree, or question it, then it can escalate into a US debate.
BBB, Dun and Bradstreet, and whatever else they are affiliated with is a good place to annoy them, and cost them a lot of money.
Honestly as you can walk into best buy and purchase a game that can only be activated on Steam, this is really becoming a court issue. Visa is giving people refunds for 6 months. I got mine, even the steam boards were full of how to get a 6 month credit on chargebacks. Valve got to the point on there forums they were deleting and banning people.
Still the banned people can play games but the consumers that didn't accept the terms can not.
Don't forget TV news, they love to report on these things if enough people complain. That will spread the word.
Write your local paper. Get people gathered together. Let people know what's really going on. The term purchase needs to be changed on the steam store. Going to the media is the perfect way to motivate someone to do it. There needs to be a disclaimer when purchasing a PC game that activating it on Steam give Steam control on if you can or cannot continue playing the game.