Does a company have an ethical responsibility to protect a customer from his own ignorance? That goes back to providing quality customer service. If the salesman, or whatever, allows a customer to purchase a product that is totally opposite of what he needs, then that customer is probably going to chose a company that can better inform him to his needs, in the future. Again, ethics = profit.
Does a company have an ethical responsibility to fund something like the Special Olympics? Well, it's good PR, so ethics = profits.
Should a company have a responsibility to fund something like a gay rights group? IMO, any company that involves itself in politics, or religion is shooting itself in the foot. Speaking from personal experience, I don't and will never allow my company to be associated with anything political, or religious, or anti-religious. In that case, what may be defined as ethical activity could mean a loss in profits.
Does a company have some responsibility to improve society, aside from the laws that regulate it's particular industry? No.
Companies exist from one reason: to exchange goods and services for money. Every company has a responsibility to itself to accomplish that goal as best it can. Engaging in ethical conduct can achieve that goal; however, "ethical conduct", maybe defined.
As a business owner, will I bend the rules to make a buck? You bet I will. Will I engage in conduct that I define as unethical? There's going to have to be a helluva lot of cash sitting on the table for me to do that. Now, if the cash is under the table? That's a different story.