Uhh can you say fire hazard !?
It's all about the wattage. The rule of thumb is that you shouldn't take more than 1500 watts from one outlet. Check the ratings on your systems and add them up. As long as you are under 1500, you can daisy-chain power strips to your heart's content, and that came straight from an electrician I know.
In my case, thanks in part to having the 2nd TV and the 360 hooked up to a different outlet across the room, I only draw 600 watts from one outlet, and that would be with every single system on at the same time, which of course is silly. Typically, the draw is less than 400.
What you want to avoid is plugging in a hair dryer, a microwave, a vacuum cleaner and a space heater into one power strip.