From the Professional Conduct section of

The BusinessWeek Code of Journalistic Ethics

d. Gifts, meals, and entertainment.
"You may not accept gifts from companies, from their public relations firms or agents, or from any other supplier of information -- not a bottle of wine during the holidays, not a reduced-rate membership for your personal use. During company visits, you may accept mementos or sample products of nominal value (less than $25). But you must refuse, return, dispose of, or donate to charity any unsolicited gifts of more than nominal value -- the choice in the latter three instances being up to the sender, whom you must contact immediately. Obviously, you may not solicit gifts.

In addition, you generally may accept lunch or dinner only from a source with whom you are likely to meet often enough to return the favor (the one exception being an interview over a meal with a source at the person's offices). In all other instances, you or BusinessWeek must pay your tab.

You must use review copies of books, video games, and the like only for editorial purposes -- or else, as practicable, forward them to a person designated by the editor-in-chief for donation to charity. You may not sell such materials for any reason.

You may accept the use of a review or test model of a new product -- cars, computers, software, and any other products, including subscription services -- for only as long as your reporting needs require. In most cases, this means only a few days -- and not for an extended period.

In situations where a company with whom BusinessWeek has an editorial partnership offers you favors, you must comply with the McGraw-Hill Code of Business Ethics, which states in part: "No gift having more than nominal value and no loan (other than a normal bank loan) may be accepted from any person or firm having current or prospective dealings with the corporation."

http://www.businessweek.com/ethics.htm

I found it interesting how specific some codes of ethics can be.