Business ethics can cover a wide range of sins.
First, unethical business practices relate to being honest with your customers. Which is why consumer protection laws exist. But for every law that exists, there is a leading bleeding edge of practices that barely skate by the boundaries of that law.
Case to consider: The business ethics of Allstate Insurance Co. making a post-Katrina damages claim based on an engineering paper written by someone who never visited the claimant's house. Ethical or not?
Second, unethical business practices relate to how you treat your employees. Which is why labor laws exist. Including things like overtime and various safety and health regulations.
Case to consider: The company has a "use it or lose it" rule regarding accrued vacation hours when the employee doesn't take vacations often enough to keep this in balance. Not "use it or have it bought back." "Use it or lose it." Ethical or not?
Third, unethical business practices relate to how you treat your competitors. Which is why intellectual property rights laws exist.
Case to consider: Lawsuits abounding between Microsoft and Apple some years ago over the concept of Windows "look and feel." Both sides sued the other over what was essentially an unwinnable case for either. (Both had stolen the point-and-click paradigm from a defunct third party whose claim on the design had lapsed.) The lawsuit was essentially a nuisance suit for both parties. Ethical or not?
When you have brushed up against a business and come away hurt or at least disappointed, in the process losing money or something else of value (measurable or not), and the people you talk to seem unresponsive, and they tell you, "It's just business, don't take it personally" ... Does that fly in the face of the concept of ethics? Which, at bottom, has to do with equity and fairness in business activities. Or are the representatives correct, i.e., it was just business and you lost out.
These are topics directed at businesses. But there are employee business ethics, too. For instance, your example of web-surfing at work when the topic is not work-related. If you are on the clock, is that stealing? If you are salaried and are paid by results, is that still theft of services? But the counter question is whether browsing a site that is full of (non-porno) eye candy as a way to relax your mind after a hard slog through rotten code helps productiviy enough that it is actually beneficial.
The issue is going to be defined by corporate culture as well as anything else. In the government, there is a heavy price to pay because of auditors trying to assure that taxpayer dollars are spent wisely and well. But in the commercial world, does the time spent away from direct production merely cause prices to go up (because of lower productivity leading to higher overhead leading to higher need to recoup costs) such that employee goof-offs are actually hurting customer pocketbooks? And is that unethical?
If you can't find some stuff to think about in the above, I can't help you.