Recently, The New York Times reported that the makers of "Cheerios" now forces its customers to give up their legal right to sue the company (i.e., to subject themselves to forced arbitration) when they engage with the company online, for example, by joining its community on Facebook. While this move is disturbing in so many ways (do companies really believe they can get out of serious product liability claims with a ToS no one even has to click assent to?), almost more upsetting is the fact that they tried to do it quietly, without informing their loyal, engaged customers what they were giving up.
General Mills is a big company, and they might be able to get away with a move like this one. But small companies should be very wary about following suit. It may be tempting to try to limit your own legal liability, but customers are increasingly savvy about web terms. And if The New York Times is going around reading ToS, you can bet other reporters are out there doing the same. So even if your users don't necessarily read the terms on your site, if you have truly egregious terms the media just might out you.
So be good to your users. Don't take away their legal rights. And if you feel you must, at least tell them about it.